An international peace conference expected to take place in Annapolis, Maryland, in the fall has to be serious and substantive, Rice said at a news conference with Palestinian President Mahmoud Abbas.
"We frankly have better things to do than invite people to Annapolis for a photo op," she said.
Israelis and Palestinians, Rice added, are making their "most serious effort" in years to resolve the conflict.
The gaps are wide and U.S. officials have indicated that the conference might be postponed, reports CBS News correspondent Robert Berger. There has been little progress on the core issues of the conflict, such as Jerusalem, Palestinian refugees and final borders.
The Palestinians want to formulate a joint document with Israel, which would at least give an outline of how to solve the key disputes in the conflict. The document must be completed before the start of the conference, which would then be used as a launching pad for a resumption of peace talks, the Palestinians say.
In contrast, Israel says the conference could be held without such a document in hand, and staunchly opposes the Palestinian idea of setting a timeline for starting and completing negotiations.
In other developments:
Palestinian negotiators were heading to Jerusalem on Monday, for an impromptu meeting with their Israeli counterparts, officials said. The two sides were to work on a joint outline of a future peace deal, said the office of the top Palestinian negotiator, Ahmed Qureia.
The meeting was set just after Rice's talks with Abbas. It was not clear whether Rice would join the two teams.
Rice is on a four-day shuttle mission, trying to create some common ground ahead of the meeting. A State Department official hinted on Sunday that the conference, expected to take place in Annapolis, Md., in late November, might be postponed because of the gaps between the two sides.
Abbas aides said they were concerned that Rice cautioned over the weekend against expecting breakthroughs during her meetings with Israeli and Palestinian leaders. She also plans a trip to Cairo and talks in London with King Abdullah II of Jordan.
"With her statement yesterday, Dr. Rice reduced the Palestinian hopes for the conference," said Nabil Amr, an Abbas adviser. "We didn't expect her to come with this direction. The U.S. is a party to this conference, and we expect it to exert efforts to make it succeed."
Abbas would also complain to Rice about recent Israeli land expropriations in the West Bank, Amr said. "This spoils the positive atmosphere that accompanied the call for the fall conference," he said.
Amr referred to land seizures for a road project that Palestinians fear is intended to tighten Israeli control over strategic West Bank areas near Jerusalem. Israel says construction is not imminent and is meant to ease Palestinian movement.
Rice delivered a rare warning to Israel not to take any steps that might erode confidence in the peace process. "This is a very delicate time," she said Sunday. "It's just a time to be extremely careful."
On Monday, Abbas and Rice met at his West Bank headquarters in the city of Ramallah.
On Sunday, Rice had held a first round of talks with Israeli leaders.
A U.S. State Department official indicated afterward that the conference, called by President Bush, might have to take place later than expected.
"This is going to take some time," the official told reporters on condition of anonymity to describe the private conversations. "This is going to require a lot of hands-on American diplomacy. These are really tough issues."
The Israelis and Palestinians are hoping to hammer out a joint statement outlining a common vision for a future peace agreement, which they hope to present at the conference.