TEHRAN (Reuters) - Iran backs all Muslim uprisings except those stirred up by Washington, Supreme Leader Ayatollah Ali Khamenei said on Saturday, a stance that explains Tehran's lack of support for anti-government protesters in ally Syria. Addressing a crowd commemorating the death of Ayatollah Ruhollah Khomeini, Khamenei said the leader of the 1979 Islamic Revolution had predicted events in the Middle East over the last few months where Arabs have risen up against oppressive regimes. Non-Arab, Iran relished the fall in February of Egyptian President Hosni Mubarak, a US-backed secularist who made peace with Israel. Tehran has also voiced support for pro-democracy movements elsewhere in the region, especially Bahrain where the Sunni monarchy was aided by Saudi Arabia and the United Arab Emirates to put down democracy protests. But the Islamic Republic, which crushed its own mass protests after the disputed re-election of hardline President Mahmoud Ahmadinejad in June 2009, has not expressed backing for demonstrators in Syria where President Bashar al-Assad is a key regional ally. "Our stance is clear: wherever a movement is Islamic, popular and anti-American, we support it," Khamenei told the crowd which punctuated his speech at Khomeini's mausoleum on the outskirts of Tehran with chants of "Death to America." Without mentioning Syria by name, he continued: "If somewhere a movement is provoked by America and Zionists, we will not support it. Wherever America and the Zionists (Israel) enter the scene to topple a regime and occupy a country, we are on the opposite side." Washington has accused Tehran of helping Syria crush protests, an accusation both countries deny. A Syrian human rights group said 63 civilians were killed in the latest clashes on Friday. Iran's adversaries fear its influence in the Middle East could increase due to the shake-up in the region where Syria has been one of its few allies. The United States and Israel say they suspect Iran uses Syria as a conduit for weapons to militant groups in Lebanon and the Gaza Strip, a charge Iran and Syria deny. The president attended the commemoration but, unlike last year, did not speak himself. One week before the second anniversary of Ahmadinejad's re-election which the opposition movement wants to mark by a "silent rally" in Tehran, Khamenei said there was room for dissenting voices as long as they did not seek to topple the Islamic system.