Iran's official IRNA news agency put the quake's magnitude slightly higher at 5.2 and said there were no initial reports of casualties or damage.
The quake also shook the larger port city of Bandar Abbas and was felt across the Gulf in Dubai, where residential and office towers shook for around 10 seconds but were not evacuated.
Iran stands on several seismic fault lines. In April last year, a 7.8 magnitude earthquake struck southeastern Iran and neighbouring Pakistan, killing 40 people.
A massive quake in December 2003 struck the southern city of Bam, killing 26,000 people and destroying its ancient mud-built citadel.