The shallow 5.9-magnitude quake struck about 120 kilometres southeast of the city of Tabriz, in East Azerbaijan Province, in the early hours of the morning.
An emergency official says a magnitude 5.9 earthquake in northwestern Iran has killed at least five people and injured over 300 others.
Pirhossein Koulivand told state TV about the deaths and injuries early Friday morning.
The shallow 5.9-magnitude quake struck about 120 kilometres southeast of the city of Tabriz, in East Azerbaijan Province, in the early hours of the morning, said the Iranian Seismological Centre.
The quake, described as "moderate", was eight kilometres deep and was followed by four aftershocks.
US Geological Survey (USGS) issued an alert warning that "significant casualties are likely and the disaster is potentially widespread."
Iran sits where two major tectonic plates meet and experiences frequent seismic activity.
The country has suffered a number of major disasters in recent decades, including at the ancient city of Bam, which was decimated by a catastrophic earthquake in 2003 that killed at least 31,000 people.
In 1990, a 7.4-magnitude quake in northern Iran killed 40,000 people, injured 300,000 and left half a million homeless, reducing dozens of towns and nearly 2,000 villages to rubble.
Iran has experienced at least two other significant quakes in recent years, one in 2005 that killed more than 600 people and another in 2012 that left some 300 dead.