President Obama pledged on Thursday to “seek a new beginning between the United States and Muslims around the world,” imploring America and the Islamic world to drop their suspicions of one another and forge new alliances to confront violent extremism and heal religious divides.

“We have a responsibility to join together on behalf of the world we seek,” he said. “A world where extremists no longer threaten our people, and American troops have come home; a world where Israelis and Palestinians are each secure in a state of their own, and nuclear energy is used for peaceful purposes; a world where governments serve their citizens, and the rights of all God’s children are respected.”

He dwelled on Iran, Iraq, and Afghanistan but reserved some of his sharpest words for the Israeli-Palestinian conflict. He offered no major initiatives on the Middle East peace process although he put Israelis and Palestinians on notice that he intends to deal directly with what he sees as intransigence on key issues, evoking the concerns of both parties but asking both to shift ground significantly.

The speech in Cairo, which he called a “timeless city,” redeemed a promise he made nearly two years ago while running for president. It was, perhaps, the riskiest speech of his young presidency, and Mr. Obama readily conceded that not every goal would be easily or quickly achieved.

“I have come here to seek a new beginning between the United States and Muslims around the world; one based upon mutual interest and mutual respect; and one based upon the truth that America and Islam are not exclusive, and need not be in competition,” he said. “Instead, they overlap, and share common principles — principles of justice and progress; tolerance and the dignity of all human beings.”

His message was sweeping and forceful — at times scolding and combative — promoting democracy in Egypt, warning Israelis against building new settlements, and acknowledging that the United States had fallen short of its ideals, particularly in the Iraq war. It also evoked a new and nuanced tone, and some of Mr. Obama’s language drew appreciative applause from his audience of 3,000 invited guests in the Major Reception Hall at Cairo University.

Several times, for instance, he spoke of “Palestine,” rather than the more ambiguous term often used by American leaders, “future Palestinian state.” And, in reference to the Palestinians, he pointedly mentioned “the daily humiliations — large and small — that come with occupation.”

He described the bond between the United States and Israel as “unbreakable,” and urged Hamas, the Islamic militant group in control of the Gaza Strip, to stop violence. But in his next breath, Mr. Obama said Israel must curtail its expansion of West bank settlements and recognize Palestinian aspirations for statehood. He also acknowledged that Hamas, which the United States labels a terrorist organization, “does have some support among some Palestinians.”

“But they also have responsibilities,” Mr. Obama said, listing them as “to end violence, recognize past agreements, recognize Israel’s right to exist.”

“Israelis must acknowledge that just as Israel’s right to exist cannot be denied, neither can Palestine’s,” Mr. Obama said. “The United States does not accept the legitimacy of continued Israeli settlements. This construction violates previous agreements and undermines efforts to achieve peace. It is time for these settlements to stop.”

And, while Israel’s hawkish government has not accepted a so-called two-state solution, Mr. Obama said: “The only resolution is for the aspirations of both sides to be met through two states, where Israelis and Palestinians each live in peace and security.”

“This is in Israel’s interest, Palestine’s interest, America’s interest and the world’s interest,” he said. In the Middle East, “too many tears have been shed; too much blood has been shed.”

The address drew initial support from Palestinians. Nabil Abu Rudeineh, a spokesman for Palestinian President Mahmoud Abbas, called it “a good start and an important step towards a new American policy.”

“It was honest, is the first word that comes to mind,” said Hossam Bahgat, executive director of the Egyptian Initiative for Personal Rights, an independent human rights organization.

Mr. Bahgat, who attended the speech at Cairo University, said that one of the most important elements of the speech was what was left out. “I think it was remarkable the speech left out the term terrorism completely,” he said. “It may have been a paradigm shift for the United States, away from using this politically charged word.”

But others in the region faulted it. The President, some noted, did not offer any new initiatives, did not lay out a time line for progress towards a Middle East settlement and asked his audience to accept an view which gave equal weight to Israeli and Palestinian concerns.

That part did not go down well, people in the region said.

“I feel it is important historically, but it will bring nothing new,” said Hasim Fouad, 24, a reporter with the independent Egyptian newspaper Al Dustour.

Mr. Obama strode onto the stage to loud applause and a standing ovation in the conference hall. He conceded that his speech came at “a time of great tension between the United States and Muslims around the world.”

But he sought to explain that he represented the new face of American leadership. He did not mention the name of George W. Bush, who preceded him in office, and whose policies contributed to the mistrust.

“America is not and never will be at war with Islam. We will, however, relentlessly confront violent extremists who pose a grave threat to our security,” Mr. Obama said. “Because we reject the same thing that people of all faiths reject: the killing of innocent men, women, and children.” Mr. Obama said: “I consider it part of my responsibility as president of the United States to fight against negative stereotypes of Islam wherever they appear. But that same principle must apply to Muslim perceptions of America. Just as Muslims do not fit a crude stereotype, America is not the crude stereotype of a self-interested empire.”

Mr. Obama offered few details for how to solve myriad problems and conflicts around the globe, but he offered up his own biography as a credible connection to his audience. While the message touched upon a litany of challenges, it boiled down to simply this: Barack Hussein Obama was standing at the podium as the American president.

“I am also proud to carry with me the goodwill of the American people, and a greeting of peace from Muslim communities in my country: assalaamu alaykum,” Mr. Obama said, delivering a common greeting signifying peaceful intent.

Mr. Obama said the terrorist attacks in the United States on Sept. 11, 2001 caused “enormous trauma to our country.” He offered no direct criticism of the previous administration, but reminded his audience that he has “unequivocally prohibited the use of torture” and has ordered the prison to be closed at Guantánamo Bay, Cuba.

“The fear and anger that it provoked was understandable, but in some cases it led us to act contrary to our traditions and our ideals,” Mr. Obama said. “We are taking concrete actions to change course.”

The president divided his speech into seven sections, often sounding like the university professor he was before he sought political office. He touched on “sources of tension” from wars in Iraq and Afghanistan, democracy, religious freedom, women’s rights and economic development and opportunity.

He said the Iraq war had been a “war of choice that provoked strong differences in my country and around the world.”

“Although I believe that the Iraqi people are ultimately better off without the tyranny of Saddam Hussein, I also believe that events in Iraq have reminded America of the need to use diplomacy and build international consensus to resolve our problems whenever possible.”

By contrast, he described America’s military presence in Afghanistan as a necessity after the attacks of Sept. 11, 2001.

“Make no mistake: we do not want to keep our troops in Afghanistan,” he said. “We would gladly bring every single one of our troops home if we could be confident that there were not violent extremists in Afghanistan, and now Pakistan, determined to kill as many Americans as possible. But that is not yet the case.”

Turning to Iran’s contentious nuclear program, he said any nation “should have the right to access to peaceful nuclear power if it complies with its responsibilities” under international regulations to counter the proliferation of nuclear weapons.

Iran maintains its nuclear enrichment program is for peaceful civilian purposes but many in the West suspect it is designed to build a nuclear bomb. “This is not simply about America’s interests,” Mr. Obama said, “It is also about preventing a nuclear arms race in the Middle East that could lead this region and the world down a hugely dangerous path.”

As his visit to the region began Wednesday in Saudi Arabia, Mr. Obama was greeted with reminders of the vast gulfs his address must bridge, as voices as disparate as Al Qaeda’s and the Israeli government’s competed to shape how Mr. Obama’s message would be heard.

In a new audiotape, Osama bin Laden condemned Mr. Obama for planting what he called new seeds of “hatred and vengeance” among Muslims, while in Jerusalem, senior Israeli officials complained that Mr. Obama was rewriting old understandings by taking a harder line against new Israeli settlements.