An additional 600 were injured, the Iranian news agency Press TV reported.
The town of Kaki, 90 kilometers (55 miles) southeast of Bushehr, was the epicenter of the earthquake, the Iranian Seismological Center reported, noting four aftershocks, jolting Kaki and the nearby city of Khour-Mowj.
The Persian Gulf states of Kuwait, Qatar and the United Arab Emirates also reported shocks from the earthquake, Press TV said.
The Russian company Atomstroyexport, constructor of a nuclear power plant near Bushehr, said the earthquake "in no way affected the normal situation at the reactor. Personnel continue to work ... and radiation levels are fully within the norm," the Russian news agency RIA-Novosti said.