The launch of surface-to-surface medium range missiles into Syria's Deir el-Zour province comes as Islamic State militants fleeing a USA -led coalition onslaught increasingly try to fortify their positions there.
The Revolutionary Guards are fighting in Syria against militant groups who oppose President Bashar al-Assad.
It was the first missile attack by Iran outside its own territory in 30 years, since the Iran-Iraq war of 1980-88, media in the Islamic republic reported.
Activists in Syria said they had no immediate information on damage or casualties from the strikes, launched from Iran's Kurdistan and Kermanshah provinces. "In case if attacks on Iran continue, the flame of our justifiable anger will burn terrorists to ashes", the Revolutionary Guards said in a statement. The Guard's website said it launched surface-to-surface medium-range missiles targeting the area.
In those attacks, ISIS-linked fighters stormed Parliament and a shrine to Ayatollah Ruhollah Khomeini.
Islamic State issued a statement claiming responsibility for the Tehran attack.
"A missile strike on militants' positions is a warning to terrorists".
"The IRGC warns the Takfiri terrorists and their regional and trans-regional supporters that they would be engulfed by its revolutionary wrath and flames of the fire of its revenge in case they repeat any such devilish and dirty move in future", the IRGC added.