Six firebombs were thrown at a synagogue in the north of Moscow on Tuesday, police said.
Shortly after midnight, the attackers hurled glass bottles filled with burning petrol at the wall of the Darkay Shalom synagogue.
No one was hurt in the attack, but the walls of the building were slightly damaged.
According to a preliminary information, it was an act of hooliganism, a police spokesperson said.
But police believe the arson may have been in response to a court ruling on Monday in which several members of the National-Socialist Society (NSO), a banned Russian neo-Nazi group, were sentenced to prison terms varying from 10 years to life in prison. They were convicted of 27 hate killings, attempted murders and plotting to blow up a power station.
Monday's hearing received national media attention and saw the group walk into court chanting neo-Nazi and anti-Semitic slogans.