The local seismological center affiliated to the Tehran University geo-physics institute registered the tremors at 20:16 hours local time Tuesday (16:46 GMT).
There have been no report of injuries or damages as yet.
Iranians are still haunted by the harrowing images of the world's worst disaster in 2003, in which more than 41,000 people were killed in the ancient city of Bam.
According to the Zurich-based Swiss Re, the earthquake in Bam on December 26 was the fourth largest in terms of victims since 1970. The third largest was the quake in Gilan, northern Iran, which left 50,000 dead in 1990.
The quake sent shudders across the Iranian capital -- a city of about 14 million -- which, some experts warn, can suffer in million if it is struck by a strong tremor.
They have warned that most of the buildings in the sprawling Iranian capital would hardly withstand a strong tremor, blaming builders.
earlier in January, Iran admitted that poor enforcement of building regulations had added to the death toll from the country's regular devastating earthquakes.
"Our country is likely to have natural disasters but our people do not deserve these losses because of mismanagement before the earthquakes occur," Interior Ministry Abdolvahed Mousavi-Lari was quoted as saying.
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