US Secretary of State Colin Powell has demanded urgent security reforms from the Palestinian prime minister, as he seeks to put the "roadmap" for peace back on track.
Powell praised Israeli moves towards implementing the roadmap
Violence between the two sides has killed about 60 people since the US-backed peace plan was launched earlier this month.
Speaking after talks in Jerusalem with Israeli Prime Minister Ariel Sharon, Mr Powell called the Palestinian militant group Hamas an "enemy of peace".
The secretary of state - who is in the region to try to salvage the beleaguered peace plan - also met Palestinian Prime Minister Mahmoud Abbas, also known as Abu Mazen.
Following this meeting, Mr Powell said he had assured Mr Abbas of President Bush's personal commitment to improving the fortunes of the Palestinians.
In a joint news conference with Mr Sharon, the secretary of state said there could be "no justification" for terrorist acts.
He said those opposed to peace must be "overwhelmed".
As the talks took place in Jerusalem, Palestinian gunmen shot dead an Israeli motorist near the West Bank city of Ramallah, rescue workers said. Three other people in the car were also hurt in the attack.
Mr Powell also said he was "encouraged" by recent steps taken by Israel, notably releases of Palestinian prisoners and the dismantling of settler outposts in the West Bank.
ROADMAP'S PATH TO CRISIS
4 June: US-Jordanian-Israeli summit in Aqaba
8 June: Palestinian militant groups reject roadmap
10 June: Israel tries to kill Hamas leader Abdel-Aziz al-Rantissi
11 June: 16 die in suicide attack on Jerusalem bus
19 June: Jewish settlers clash with Israeli troops dismantling a West Bank outpost
Mr Powell is to go on to the West Bank city of Jericho for talks with Abu Mazen later on Friday.
The US secretary of state said he would urge the Palestinian prime minister to implement security reforms quickly.
Israel and the Palestinian Authority are engaged in talks on replacing Israeli troops in northern Gaza with Palestinian security forces.
Earlier, Mr Powell said he believed there was some movement in Abu Mazen's talks with militant groups, but a ceasefire would not in itself be enough.
"I view a ceasefire... as just one step toward eliminating the capability to conduct terrorist acts," he said.
Mr Sharon, for his part, reaffirmed his support for the roadmap, as the peace plan is called.
He described incidents surrounding the dismantling of settlement outposts as the "birth pains" of the peace process.
ROADMAP MAIN POINTS
Phase 1: End to Palestinian violence; Palestinian political reform; Israeli withdrawal and freeze on settlement expansion; Palestinian elections
Phase 2: (end of 2003) Creation of an independent Palestinian state; international conference and international monitoring of compliance with roadmap
Phase 3 (2004-2005): Second international conference; permanent status agreement and end of conflict; agreement on final borders, Jerusalem, refugees and settlements; Arab states to agree to peace deals with Israel
On Thursday Israeli troops began dismantling the outpost of Mitzpeh Yitzhar, near Nablus.
There were clashes at the hilltop encampment on Thursday as hundreds of settlers tried to prevent soldiers removing the outpost, a collection of huts and tents housing eight families.
The BBC's James Reynolds, who was at the site, said some of the settlers placed a pile of stones in the road to block the army's way, and when soldiers removed the stones, the settlers put them straight back.
Settlers also set fire to some of the surrounding scrubland to try to prevent soldiers reaching the site.
Israel has agreed to dismantle settlement outposts built without government authorisation as part of its obligations under the roadmap.
Many of the outposts which have been taken down are uninhabited, or contain few occupants, and many Palestinians view their removal as a largely cosmetic operation.
Israel has refused to ban building on the larger legal settlements, despite the freeze demanded by the peace plan.