The quake, which registered 5.5 on the moment magnitude scale, hit at 8:38 pm (1708 GMT). Its epicentre was 25 kilometers from Zohan, a small town in South Khorasan province, Tehran University’s Seismological Centre said.
The US Geological Survey, which monitors earthquakes worldwide, confirmed the temblor, said it measured 5.6 and was at a depth of 5.4 kilometers.
Iranian state television said emergency crews were dispatched to the area.
Zohan is about 810 kilometres southeast of Tehran.
Iran sits astride several major fault lines and is prone to frequent earthquakes, some of which have been devastating.
In December 2003, a quake measuring 6.6 on the Richter scale struck the southern city of Bam. It killed 31,000 people — about a quarter of the population — and destroyed the city’s ancient mud-built citadel.