There were no reports of casualties in the south, but state news channels said there was extensive damage in the region mainly because most of the homes there are made of mud and brick.
"Due to the old and traditional structure of the buildings, the quake damaged 700 houses," Ali Reza Kazemi, mayor of the southern region of Negar, said.
Iranian TV footage showed parts of buildings reduced to rubble and homes strewn with shattered glass and other debris.
Communications were also temporarily disrupted by the earthquakes.
Earthquakes and tremors are common in Iran, which is located on seismic fault lines.