It said the quake occurred at 11:53 p.m. (3:23 p.m. ET) and was centered 15 miles north of Dezful toward the Iraqi border. It was only 6.2 miles deep.
Iranian media carried no immediate reports on the quake, or any damage it may have caused.
The town of Dezful had a population of 235,819 as of the 2006 census.
A magnitude 5.0 quake is considered moderate and can cause considerable damage.
(Reporting by Sandra Maler; Editing by Peter Cooney)
