Egyptian President Mohamed Morsi has said it is an "ethical duty" to support the Syrian people against the "oppressive regime" in Damascus.
His speech at the Non-Aligned Movement summit in Tehran on Thursday prompted a walkout by the Syrians.
"Our solidarity with the struggle of the Syrian people against an oppressive regime that has lost its legitimacy is an ethical duty as it is a political and strategic necessity," Morsi said.
"We all have to announce our full solidarity with the struggle of those seeking freedom and justice in Syria, and translate this sympathy into a clear political vision that supports a peaceful transition to a democratic system of rule that reflects the demands of the Syrian people for freedom."
Al Jazeera's Imran Khan, reporting from the summit, said: "Morsi's comments have caused an unease feeling, especially for the Iranians who are close to Syria."