Two strong earthquakes struck on Saturday near the northwestern city of Tabriz, sparking panic, Iranian media said without giving immediate reports of casualties or damage.
The first quake registered 6.2 of the moment magnitude scale and hit at 4:53 pm (1223 GMT) with an epicentre just 60 kilometres (40 miles) from Tabriz, Tehran University's Seismological Centre said.
An aftershock measuring 6.0 followed at 5:04 (1234 GMT), the centre said.
Mehr and Fars news agencies said the temblors disrupted mobile and fixed telephone communication, making it difficult to access information from the area.
Both said terrified Tabriz inhabitants, many of whom had been at home observing the Ramadan fast, left their shaking homes and ran into the street for safety.
Tabriz has a population of around 1.5 million people.
The US Geological Survey, which monitors earthquakes worldwide, confirmed the tremors. It measured the first at 6.2 and the second at 6.3 on the moment magnitude scale measuring energy released.
Iran sits astride several major faultlines and is prone to frequent earthquakes, some of which have been devastating.
In December 2003, a quake measuring 6.6 on the Richter scale struck the southern city of Bam, killing 31,000 people -- about a quarter of the population -- and destroying the city's ancient mud-built citadel.