Iran has urged Ankara and Damascus to show "restraint" over Syria's shooting down of a Turkish fighter jet, Iranian state media reported on Sunday.

Tehran "asks both sides to show calm and restraint, and hopes that with tact and tolerance and dialogue this issue will be evaluated and through a peaceful resolution, tranquillity and stability will be preserved in the region," Foreign Minister Ali Akbar Salehi was quoted as saying.

Iran is the staunchest ally of Syria, which is embroiled in a 15-month conflict UN officials fear has become a civil war.

Turkey, a NATO member, sits on the other side as a critic of Syrian President Bashar al-Assad's vicious crackdown against the unrest.