William Hague, who is touring the region, said it could "lose further momentum" if international focus shifts to countries like Tunisia and Egypt.
He urged Israel to avoid "belligerent language" and called for "bold leadership" from the United States.
Protests are continuing in Egypt with the aim of ousting the president.
Last month, Tunisia's President Zine al-Abidine Ben Ali stood down after weeks of anti-government demonstrations.
His exit sparked a wave of similar uprisings elsewhere, most prominently in Egypt, where protesters were back on the streets in large numbers on Tuesday demanding the immediate resignation of President Hosni Mubarak.
There have also been anti-government demonstrations in Jordan - where King Abdullah dismissed his government - and in Yemen, where President Ali Abdullah Saleh announced he would not stand for re-election in 2013.
'Legitimate fear'
Mr Hague is currently on a three-day tour of north Africa and the Middle East.
In an interview on his way to Jordan, he voiced concerns about the future.
"Amidst the opportunity for countries like Tunisia and Egypt, there is a legitimate fear that the Middle East peace process will lose further momentum and be put to one side, and will be a casualty of uncertainty in the region," he said.
"Part of the fear is that uncertainty and change will complicate the process still further. That means there is a real urgency for the Israelis and the United States."
Mr Hague spoke after Israeli Prime Minister Benjamin Netanyahu vowed to "reinforce the might of the state of Israel" whatever the outcome of the unrest.
Responding directly to those words, the foreign secretary said: "This should not be a time for belligerent language."
He added that without action now, "within a few years, peace may become impossible".
He re-iterated his feelings in a message on the micro-blogging website Twitter, saying: "Time for bold leadership on Middle East Peace Process from the US & equally bold steps by Israelis and Palestinians".
BBC diplomatic correspondent James Robbins said Mr Hague's blunt language was a reflection of his frustration at Israel's refusal to compromise on settlement building in and around Jerusalem, and the Obama administration's failure to set a clear timetable for negotiations.
While in Tunisia - his first calling point - Mr Hague met senior members of the interim government and offered the UK's assistance to help build democratic institutions.
He also announced the creation of the Arab Partnership Initiative, which will provide £5m of funding to support reform projects across the wider region.
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