The demonstration broke out as Bush met separately with Italian Prime Minister Romani Prodi and Pope Benedict XVI.

While 10,000 police officers were deployed, the protesters marched through the streets, carrying rainbow-colored peace flags and banners reading "No to Wars" and "Bush out," Voice of America reported. At Piazza Venezia, demonstrators threw bottles and other objects at police, who then fired tear gas.

Bush urged continued progress on independence for Kosovo. A White House spokesman said Bush and Prodi agreed on the importance of engaging the United Nations Security Council and moving toward implementing the plan for independence of the Balkan state.

The pope expressed to Bush his concern about the continuation of the war in Iraq and the hundreds of thousands of Iraqi Christians forced into exile, BBC News reported. The pope also said he would like to see a "regional and negotiated" solution to conflicts in the Middle East.

Bush's tour of Europe winds up with visits to Albania and Bulgaria before the president returns to Washington Monday.