TV footage shows Iranians kidnapped in Syria
Iran is seeking the release of 48 Iranians kidnapped on Saturday.
Iranian diplomats and Syrian state television blamed the abduction, which took place near the shrine of Sayyida Zainab in a suburb of Damascus, on "armed groups".
It comes as military sources report more than 20,000 Syrian troops massed around Aleppo, as fighting rages for control of the country's second city.
The BBC's Jim Muir reports from neighbouring Beirut.
Footage from Al Arabiya