On Monday, Rice also asked Syria to cooperate with the UN probe into the murder of former Lebanese prime minister Rafiq al-Hariri.
Speaking after chairing a multilateral ministerial meeting on Lebanon on the sidelines of the UN General Assembly in New York, she said participants wanted "full (Syrian) cooperation with the Mehlis (UN) investigation and that the truth be found whatever that truth is".
She also said Damascus must remain "true to the letter and the spirit of (UN Security Council) resolution 1559", which calls for dismantling all militias in Lebanon.
Rice said that meant all Syrian troops and intelligence personnel should be out of Lebanon "because Lebanon has to be free of foreign interference".
"It is clear that Syria needs to get on the right side of the events that are going on in the Middle East, that means to cut off the routes that insurgents are using to use Syrian territory to penetrate into Iraq, to close off support to Palestinian rejectionists who are the single biggest threat to progress in the Israeli-Palestinian rapprochement," Rice added.
The meeting, called to increase Syria's international isolation, brought together Rice, Lebanese Prime Minister Fouad Siniora, UN Secretary-General Kofi Annan and the foreign ministers of France, Britain, Egypt, Italy, Russia and Saudi Arabia.
European Union foreign policy chief Javier Solana also took part.