In his weekly Saturday radio address released Friday, Mr. Bush called Russia's invasion of Georgia "completely unacceptable." He urged Russia to respect Georgia's sovereignty and territorial integrity and honor its pledge to withdraw forces from Georgian territory.
President Bush said the United States will continue to deliver humanitarian aid to Georgia and he called on Russia to keep open all lines of communication and transport.
On Friday, U.S. Secretary of State Condoleezza Rice expressed support for Georgia's independence and democratic system, at a news conference in Tbilisi with Georgian President Mikheil Saakashvili.
Rice said Russian troops must immediately withdraw from Georgia under a cease-fire agreement.
A senior U.S. official said Russian foreign minister Sergei Lavrov assured Rice that Russia will implement the cease-fire, when she called him after leaving Tbilisi. It is not clear whether Russian President Dmitri Medvedev has actually signed the agreement.
Mr. Saakashvili said he signed the cease-fire after getting "clarifications" from the French, who negotiated the deal earlier this week.
In Paris, French President Nicolas Sarkozy said the way is now open for a U.N. Security Council resolution that will end the crisis.
Earlier Friday, President Bush called Georgia a "courageous democracy." He said a contentious relationship with the West is not in Russia's interests, and that the use of "bullying and intimidation" is not an acceptable way to conduct foreign policy.
German Chancellor Angela Merkel also stressed support for Georgia's territorial integrity and called Russian actions in Georgia disproportionate.
She spoke after talks in Russia's Black Sea resort of Sochi with Mr. Medvedev, who expressed doubt that residents of Georgia's breakaway regions of Abkhazia and South Ossetia will ever accept being part of Georgia.
British Prime Minister Gordon Brown spoke over the phone with Mr. Saakashvili Friday. A statement from his office said Mr. Brown described Russia's incursion into Georgia as "completely unjustified."
In her comments Friday, Rice said the United States favors the deployment of an "impartial" international peacekeeping force in Georgia.