Unknown assailants set off an explosive device made up of small gas canisters and a vessel containing petrol outside the Konstantinos Mistotakis Foundation in downtown Athens on Monday night.
The blast occurred at around 11 p.m. and caused limited damage, mainly scorching the facade on the building on Psaromilingou Street in the area of Kerameikos.
A car belonging to a New Democracy lawmaker was broken into on Friday in an area near the Acropolis in central Athens.
According to reports, the service revolver of the MP's bodyguard which had been inside the car was also stolen.
An investigation was launched to identify and arrest the perpetrator or perpetrators.
Greece has officially entered the new year and the new decade with pomp and show, as well as calls for unity.
Celebrations are in full swing across the country with fireworks and music shows taking place in major cities.
Party-goers gathered at Syntagma Square in central Athens as they awaited the final countdown which was attended by new city mayor Kostas Bakoyannis.
The leftist opposition party Monday criticized the conservative administration for failing to nominate a candidate for Greece's presidential elections next year.
Incumbent Prokopis Pavlopoulos' term officially expires on February 15. SYRIZA has said it will back Pavlopoulos, a conservative, if he is nominated by ruling New Democracy.
The government welcomed the central bank's interim report on monetary policy on Friday, saying it confirms the "realistic optimism" of Prime Minister Kyriakos Mitsotakis' cabinet, sources from ruling New Democracy said, adding that the report submitted to the Greek Parliament also confirms the entry of the Greek economy into "an upward spiral."
Α group calling itself Mayhem Squads has claimed responsibility for a barrage of arson attacks involving gas canisters around Athens in the early hours of last Tuesday.
Targets included the Alimos marina, a private security company vehicle stationed in Peristeri, a cafe owned by a New Democracy candidate in Kifissia, and the residence of a police reporter in Nea Ionia.