US Secretary of State Condoleezza Rice has made a rare warning to Israel not to do anything that might erode confidence in the peace process.
Ms Rice will visit Israel, the West Bank and Egypt
At the start of her latest Middle East visit, Ms Rice told reporters Israel's revival of a West Bank road-building project could hamper negotiations.
She met Israeli Prime Minister Ehud Olmert and will meet Palestinian President Mahmoud Abbas on Monday.
Ms Rice is trying to pave the way for a US peace conference next month.
Israeli and Palestinian negotiators have been trying to produce a joint document agreeing a framework for the November summit.
Ms Rice, who also met Israeli Defence Minister Ehud Barak on Sunday, told journalists her trip was unlikely to produce a breakthrough on the statement.
But the acting Palestinian foreign minister warned that without a framework jointly agreed with Israel setting out specific differences, they would not attend the conference.
Israel, however, wants a more general statement and Mr Olmert's spokeswoman said the prime minister did not believe a joint document was a precondition for the summit.
Responding to a question about Israeli confiscation of Arab land last week, Ms Rice told reporters on the plane to Tel Aviv the timing of the move had been too sensitive.
"The point that I will be making is that we have to be very careful as we are trying to move toward the establishment of a Palestinian state about actions and statements that erode confidence," Ms Rice said.
Israel insists the land was earmarked for a road-building project to help connect Palestinian communities.
But Palestinians claim it is designed to increase Israeli control over the West Bank.
Also on Sunday, Mr Olmert appointed Foreign Minister Tzipi Livni as Israeli chief negotiator on the conference.
Ms Livni has previously warned against moving too quickly towards an agreement.
Ms Rice will also visit Egypt, and later meet Jordan's King Abdullah in London on her latest round of shuttle diplomacy.
Palestinians and Israelis have said the peace talks must succeed
Correspondents say there is growing scepticism among Arab governments about next month's conference.
Washington hopes for wide Arab participation. But Syria has already said it is unlikely to attend unless its concerns over the Golan Heights are on the agenda.
Invitations for the gathering - scheduled to take place in Annapolis, Maryland - have not been sent out yet because so much remains to be finalised.
Analysts say key bones of contention will include the shape of final borders, sovereignty over Jerusalem and a solution for Palestinians who lost their homes in the war that followed Israel's creation in 1948.
Ms Rice arrived in the Middle East after visiting Moscow, where talks on US plans for a missile shield in Eastern Europe broke down after Russian President Vladimir Putin made clear his anger over the project.