According to the Seismological Center affiliated to the Institute of Geophysics of Tehran University, the quake occurred at 16:09 hours local time (12:39 GMT).
There was no immediate report on the possible casualties or damages.
Iran sits on several major seismological fault lines, making it one of the world's most quake-prone countries.
1420**2050
Follow us on Twitter @IrnaEnglish
Tehran, Jan 27, IRNA -- An earthquake measuring 4.2 on the Richter scale hit Polsefid, Mazandaran Province, northern Iran on Saturday.