A group of young masked men attacked a platoon of riot policemen guarding the ruling Syriza party's offices in central Athens with firebobmbs early Sunday.
The police responded with tear gas. Seven people were detained but released later.
Three cars and a bike parked nearby were damaged by the firebombs.
Earlier in the night, a riot police detachment was attacked in a similar manner in the Athens neighborhood of Exarchia, near the Ministry of Culture.
Such attacks occur frequently, and perpetrators are almost never arrested.
“Syriza is not cowed by criminal actions of marginal elements,” the ruling party, often accused by its opponents of being too close to these “marginal elements,” said in a statement.