At a joint news conference with Palestinian leader Mahmoud Abbas in the West Bank city of Ramallah on Saturday, Rice urged Israel and the Palestinians to coordinate the planned Israeli pullout from Gaza, calling such cooperation "absolutely critical".
She also said Washington would continue to boycott the Islamist movement Hamas, which is to stand in legislative elections that appear likely to take place early next year.
Rice said the Palestinian Authority still needs to do much more work on security reform.
"President Abbas has taken some good concrete steps towards security reform, but of course much more needs to be done," she said.
Rice said the US "applauds" Abbas's comitment to political reform and democratic soceity".
She added: "We will work with the international community to support you and the Palestinian people in these efforts.
"We must all focus on the disengagement as our best chance to re-energise the road map."
Ready to cooperate
Palestinian leader Mahmud Abbas, on his part, told Rice his government was ready to fully coordinate with Israel on the forthcoming withdrawal from the Gaza Strip.
Earlier in the day, Rice headed straight to Jerusalem after landing at Tel Aviv's international airport.
The first leg of a six-day trip that will also take her to Jordan, Egypt and Saudi Arabia before she attends international conferences in Brussels and London.
The chief US diplomat was travelling to the region at the behest of President George Bush to help nail down details of Israel's plan to pull its troops and settlers from Gaza and parts of the West Bank starting in mid-August.
Rice praised Palestinians for
building up security services
Rice said her main concern was coordination of what started out as a unilateral Israeli move.
She said "six or seven" issues had to be made clear, including security, the handover to Palestinian institutions, distribution of assets and freedom of movement.
"There needs to be clarity between the two sides about what to expect," she told reporters aboard her flight to Jerusalem.
"That I think will lead to less confusion in what is likely to be under the best of circumstances a pretty complicated set of days."
But the secretary also expected the parties to live up to their obligations to make the pullout a success and move on to implement an internationally drafted "roadmap" to end nearly five years of bloodshed.
She praised the Palestinians for making a start in streamlining and professionalising their security services, saying: "I think they are making progress on that."
But she added, "In terms of their ability to fight terror, what they do on a day to day basis, frankly I do think more can be done".
"Obviously that means that the calm he has discussed with the various Palestinian factions is going to have to hold."
US Secretary of State
"I'm certainly going to talk with President Abbas about the need for the Palestinians to play a critical role in providing a secure environment, which the Gaza disengagement can take place," Rice said.
"Obviously that means that the calm he has discussed with the various Palestinian factions is going to have to hold." She also called on the Palestinians to end "revolving-door arrests" of militants and deal with the stockpiling of weapons by the militant group Hamas.
Warning to Israel
Rice also had tough words for Israeli plans to expand Jewish settlements, east of Jerusalem, that have drawn vocal protests from the Palestinians.
"We don't intend that the Israelis try to create facts on the ground," she said. "They simply cannot engage in activities that are supposed to somehow pre-judge a final status outcome."
Palestinians will take up the
settlement issue with Rice
The Palestinians will use their own sessions with Rice on Saturday to urge her to pressure Sharon on a range of issues such as prisoners and settlements.
Ahmed Majdalani, a Palestinian cabinet minister without portfolio, said it was in Washington's interests to halt Israel's settlement activity in the West Bank and construction of a separation barrier across the territory.
"These issues are the main obstacles to the realisation of President Bush's two-state vision," he told AFP.
Abbas, who met Bush last month, has been pressing for reassurances that Gaza was not the ultimate concession by Israel and the roadmap process would go forward afterward.
Rice said: "We've been clear with the Israelis that it cannot be Gaza only, that there has to be a day after the successful withdrawal from the Gaza."
Rice said a successful Gaza handover would "lead to greater confidence between the parties, greater trust between the parties and, I believe, an ability to accelerate progress on the roadmap."
The trip was Rice's first big swing through the Middle East since becoming secretary of state in January. She made a brief stop in Israel and the West Bank in February and a lightning trip to Iraq in May.
Rice's talks in Jordan, Egypt and Saudi Arabia were expected to focus on the Bush administration's drive for democratic reforms. She was to deliver a policy speech on the subject on Monday in Cairo.
Rice will move on to Brussels on Wednesday for a meeting co-sponsored with the European Union on boosting efforts to stabilize and rebuild Iraq.
She will wind up her trip in London to attend a ministerial meeting ahead of the Group of Eight summit in Gleneagles, Scotland on 6-8 July. The meeting is expected to be dominated by aid to Africa.