CAIRO — The escalating conflict in Gaza has confronted President Mohamed Morsi of Egypt with a wrenching test of his commitments — to his fellow Islamists of the militant group Hamas and to Egypt’s landmark peace agreement with Israel.

Over two days, Mr. Morsi, a former leader of the Muslim Brotherhood who has denounced Israelis as “vampires” for the killing of Palestinian civilians, seemed to reach for every diplomatic gesture he could make without jeopardizing the treaty.

“The Egyptian people, the Egyptian leadership, Egyptian government and all of Egypt is standing with all its resources to stop this assault, to prevent the killing and bloodshed of the Palestinians,” Mr. Morsi declared on Thursday in a televised address. “Israelis must recognize that we do not accept this aggression.”

But with Israel and Hamas increasing their attacks and a possible Israeli ground assault looming, Mr. Morsi finds himself in a tighter bind. As Egypt’s first freely elected president, he faces popular demands for a radical break with former President Hosni Mubarak’s perceived acquiescence during an Israeli assault against the Palestinians in 2009. But at the same time, Mr. Morsi desperately needs to preserve the stability of the cold peace with Israel in order to secure Western aid and jump-start his moribund economy.

Aware of his divided loyalties, both sides appear to be testing him. Hamas, the Islamist Palestinian offshoot of Egypt’s Muslim Brotherhood, is pushing to see how much support it can draw from its ideological big brother now that it governs the largest Arab state. And Israel’s hawkish leadership seems determined to probe the depth of Mr. Morsi’s stated commitment to the peace treaty as well.

“We are testing the Egyptians,” said Professor Efraim Inbar, director of the Begin-Sadat Center for Strategic Studies at Bar Ilan University. “The Americans are with us on Hamas. Obviously Morsi supports Hamas and not us.”

Mr. Morsi has so far taken diplomatic steps to signal his displeasure with Israel. He recalled Egypt’s ambassador to Tel Aviv and dispatched his prime minister on a solidarity mission to Gaza. He appealed to President Obama, the United Nations, the European Union and the Arab League to try to stop the violence.

Mr. Morsi also opened Egypt’s borders and hospitals to Gaza residents injured in the clashes and offered military helicopters to transport them. He met with top generals, and Egyptian state media reported that they were inspecting air bases and preparing land defenses near the Gaza border. He has not, however, threatened to provide military support to Hamas or direct action against Israel.

Inside Egypt, the alacrity of Mr. Morsi’s response so far appears to have rallied the public behind him. Opposition to Israel’s occupation of the Palestinian territories and treatment of their residents may be the only cause binding together Islamists, their secular critics and even the leadership of Egypt’s Coptic Christian church. Some of Mr. Morsi’s rivals, including the former presidential candidate Amr Moussa, have commended his actions.

“He is doing everything he can within the legal obligations of Egypt’s relationship with Israel,” said Emad Shahin, a political scientist at the American University of Cairo, arguing that Mr. Morsi’s swift action would enable him to hold at bay the inevitable calls for Egypt to go further.

Still, popular anger and demands for more action could grow, especially if Israel initiates a ground invasion of Gaza. The Muslim Brotherhood, which backed Mr. Morsi for president, issued a statement denouncing “the criminal aggression” and blaming Arab states for “watching the shedding of Palestinian blood without moving a muscle.”

“We think the least that could be done is to sever diplomatic and commercial relations with this cruel entity,” the Brotherhood statement added, referring to Israel. “The Egyptian government has to be the first to do this in order to set an example for Arabs and Muslims.”

The ultraconservative Islamists of the Al Nour party charged that Mr. Morsi’s steps “weren’t enough” and that “additional steps are necessary to deter the perpetrator and to legally pursue the criminals until revenge is exacted against them.”

In the streets, protesters burned an Israeli flag outside the Arab League off Tahrir Square in Cairo. Leaders of the ministry that oversees mosques and religious institutions, unmuzzled by Mr. Mubarak’s ouster, called on Muslim preachers at Friday prayers to rally support for Gaza.

Since the Brotherhood won leadership of the Egyptian Parliament and Hamas broke with its former sponsor Syria, the relationship between the two groups has become both closer and more complicated. The Brotherhood has welcomed a parade of Hamas leaders in Cairo, but it has also urged the group to maintain tranquil relations with Israel so that Hamas can try to steer Egypt through its difficult political transition, for the long-term well-being of both Islamist groups, their leaders have said.

Leaders of the Brotherhood’s Freedom and Justice Party have said they planned to step back from Hamas to try to broker a reconciliation between the group and its Western-backed rival faction, Fatah, which controls the Palestinian Authority in the West Bank. Hamas has not recognized Israel, but the Brotherhood long ago came to support a two-state solution as envisioned by the Camp David accords.

In some ways, Mr. Morsi may have disappointed Hamas. He has not opened Egypt’s border to Gaza. In fact, he has moved more aggressively than Mr. Mubarak to try to shut down or blow up smuggling tunnels from the Egyptian Sinai long used by Hamas to circumvent an Israeli boycott, contending that they pose a security risk to Egypt.

But on Thursday, Hamas leaders basked in Mr. Morsi’s public support. “The popularly elected Egyptian leadership is giving everyone a lesson,” Hamas’s leader, Khaled Mashaal, told an Islamist conference in Khartoum, Sudan. “The Egyptian leadership has shown that it is taking a new course and adopting a new vision. The era when Israel did what it pleased is over.”

In Gaza, Ismail Haniyeh, the Hamas prime minister, said in a televised address that “the Arab and Muslim cities were all in silence, but we found a quick response from the Egyptian leadership.” He added: “Leaders can no longer sit on their hands while seeing our people preyed on.”