The epicenter was near Borazjan, site of the country’s only nuclear power plant.
The shaking lasted for about 20 seconds at 5:21 p.m. local time and was followed by more than 40 aftershocks.
The U.S. Geological Survey said the temblor struck at the relatively shallow depth of about 10 miles, which resulted in stronger shaking at the surface than from deeper quakes.
The state-run Islamic Republic News Agency said buildings were damaged and electricity was disrupted to several areas, including sections of Borazjan.
Iranian President Hassan Rouhani said he was “deeply saddened” to hear of the fatalities, expressing condolences to the grieving families.
A stronger quake that struck just to the south last April killed 37 and devastated two villages.