Rice also pressed Syria on the political front, stressing that she hoped the reinstatement of a pro-Damascus prime minister, who resigned earlier after anti-Damascus protests, would only be "temporary."
The top US diplomat cautiously welcomed Syria's withdrawal of its troops from northern Lebanon. But with others remaining in parts of its small neighbor, Rice reiterated the US demand for all Syrian forces to leave.
"It's not a bad thing that Syrian forces are moving - clearly not a bad thing - but it is also not compliance with 1559," she said, referring to a UN resolution, which calls for all Syrian forces to leave.
"If there's an ultimatum, it's 1559. It's get out," she added.
On Friday, the last Syrian troops in north Lebanon left for home, underlining Damascus's diminishing role in its neighbor.
Syrian troops have withdrawn
from north Lebanon
Syrian forces first entered Lebanon in 1976, early in the country's civil war. Their numbers have declined to 14,000 from a peak of 40,000, but they had never before abandoned the north.
Syrian troops also continued to return home or move eastward from the Beirut area in line with a phased withdrawal plan agreed this week after US-led global demands on Damascus to lift its military and political grip on Lebanon.
It was not clear how many Syrian soldiers have gone home since the redeployment began on Tuesday, and Rice said she did not have any count. Nor is it clear if the troop movements mean Syria is withdrawing all of its forces from Lebanon.
Rice said she hoped UN envoy Terje Roed-Larsen, due to meet Syrian President Bashar al-Asad in Damascus on Saturday, could "get greater clarity about Syria's willingness to comply with 1559".
"It's not a bad thing that Syrian forces are moving - clearly not a bad thing - but it is also not compliance with 1559"
US Secretary of State
The United States has pushed for the Syrian withdrawal as a way to reduce Damascus's influence ahead of Lebanese parliamentary polls due by May.
But Lebanon lurched into a deeper political crisis on Friday, threatening the timing of the elections.
In Beirut, the opposition indicated it would spurn a call made by the reinstated pro-Syrian Prime Minister Umar Karami for a national unity government. The opposition's resistance sets the stage for a political standoff that could force the general election to be postponed.
Karami was reappointed on Thursday after his pro-Syrian Cabinet fell last week over the assassination of former Prime Minister Rafiq al-Hariri.
Asked how the United States viewed Karami's reinstatement, Rice said, "I would hope that's just a temporary measure."
The United States had welcomed Karami's resignation as a sign of people power after it perceived anti-Syrian protests as expressing a hunger for greater democracy in Lebanon.
But this week, there were even larger anti-American, pro-Syrian protests in Lebanon. Many political analysts said the larger demonstrations showed the limits to US influence over a country, where there is wide support for the resistance Hizb Allah group.