The Athens Institute of Geodynamics gave the natural disaster a preliminary magnitude of 5.1 but the U.S. "I urge members of the public to remains calm, in Greece we are well acquainted with earthquakes", he said.
A police officer stands on a street next to a damaged auto following an quake in Athens, Greece, July 19, 2019. "But we need more time and data to have a clear picture".
News media have also reported electricity outages but internet connections were still operating.
The quake is the first to hit the Greek capital since 1999.
Earthquakes are common in Greece and neighboring Turkey.