The state TV said the quake jolted the country of Sisakht, about 500 kilometers (310 miles) south of the capital, Tehran. The reports said search and rescue teams have been deployed to the area.
It said the temblor struck at a depth of 10 kilometers (6.2 miles).
Sisakht is a farming area with a population of about 6,000 people; its part of the province of Kohkiluyeh and Boyer-Ahmad.
There were no further details on possible damages or casualties.
Iran lies on major seismic faults and experiences one earthquake a day on average. In 2003, a magnitude 6.6 earthquake flattened the historic city of Bam, killing 26,000 people. A magnitude 7 earthquake that struck western Iran in 2017 killed more than 600 people and injured more than 9,000.