Iranian state media said it struck near the town of Sisakht.
"People in Sisakht and town of Yasuj left their homes in panic. Gas and electricity has been cut off in Sisakht," a local official in the province of Kohgiluyeh and Boyer Ahmad told TV.
"Rescue teams have been dispatched to the area."
Iran is crisscrossed by major geological fault lines and has suffered several devastating earthquakes in recent years.