According to the Seismological Center of the Geophysics Institute of Tehran University, the tremor occurred at 21:08 hours local time (17:38 GMT) and at the depth of 7 km underground.
The epicenter of the quake was located at 45.50 degrees longitude and 38.29 degrees latitude.
No report has so far been released on the likely casualties or damage to property.
Iran sits on major fault lines and is prone to near-daily earthquakes.
9376**1424
Follow us on Twitter @IrnaEnglish