The quake happened at 2:46 AM local time on Saturday at a depth of 7 kilometers.
Its epicenter was near Ghaleh Khajeh region. There are no reports of casualties or damage yet.
A 4-magnitude tremor also hit Khuzestan at 21:00 PM local time on Friday.
Nearly all parts of Iran are criss-crossed by fault lines that have made the country quake-prone.