A group of about 20 to 30 people attacked migrants and stores managed by immigrants on Amerikis Square in central Athens late on Tuesday.
According to reports a number of stores managed by migrants were targeted, while the offices of the Tanzanian community in Athens were also damaged.
Some witnesses alleged that police forces present at the scene of the attack made no attempt to stop the violence, while local residents who reacted to the incident were verbally abused by the attackers.
An edited video of the incident appears to show riot police walking away from the scene and a member of the DIAS motorcycle-riding squad revving his bike as some members of the group chase a migrant and urge him to run. The images have not been verified and the police has not commented.