A wave of low-scale attacks aimed at journalists and politicians struck the Greek capital Athens over the weekend.
The politically-motivated attacks appear to be the work of left-wing anarchist militants but no group has claimed responsibility for the attack.
Gunmen fired at the headquarters of the ruling party, New Democracy, early Monday, said Reuters.
Nine rounds were fired into the windows using a Kalashnikov assault rifle.
There were no injuries and police are still investigating the shooting.
All of the parties condemned the attack reported the Associated Press.
"No act of terrorism is going to scare us," Makis Voridis, a spokesman for New Democracy said, according to the news agency.
"Our efforts to restore law and order ... will continue unobstructed."
Monday's attack followed the firebombing of the homes of five Greek journalists several days ago.
RT reported the targets were the editor of the state-run Athens News Agency, two reporters from the state-run NET television station and two presenters from the private station Mega.
Left-wing groups have long condemned many of Greece's major media stations, claiming that they do the bidding of the Greek government and business elite.
Arsonists also targeted the home of the brother of a government spokesperson, breaking down his door and throwing a firebomb into the house.
There have been no injuries in the attacks.
The incidents appear to follow the clearing of two major squatter houses where many of Greece's anarchist followers live, mainly in the Exarchia neighborhood of central Athens.
Greece has a long history of left-wing political violence until a major crackdown before the 2004 Olympics.
The 17 November group targeted journalists, politicians and businesspeople in Greece until it was broken up in 2002.
The country has seen fresh tension of left versus right violence in recent years due to the country's economic collapse.