(CNN) -- International envoy Kofi Annan said Tuesday he sees Iran as a factor in diplomatic efforts to forge peace in Syria, a stance not shared by the United States.

"I think Iran can play a positive role," Annan said during a news conference with Iranian Foreign Minister Ali Akbar Salehi in Tehran.

His remarks came a day after he met with Syrian President Bashar al-Assad in Damascus. Annan said al-Assad agreed on "an approach" to ending the 16 months of bloodshed in his country.

World powers have deplored al-Assad's government for its assaults against civilians.

But the diplomatic wranglings, such as Annan's recent Action Group meeting in Geneva and the U.S. and Arab-backed Friends of Syria initiative, have failed to stop the killings of thousands since March 2011.