ATHENS, Dec. 30 -- The Greek government on Monday strongly condemned the attack on the German ambassador's residence here, calling it an act of terrorism aimed at damaging Greece's image ahead of it assuming the rotating EU presidency.

A group of four gunmen opened fire early Monday outside Ambassador Wolfgang Dold's house in the northern suburb of Halandri, causing no injuries or major damage. Dold was inside the house when the attack happened.

"The Greek government expresses its abhorrence and utter condemnation of today's cowardly act of terrorism, the sole and obvious target of which was Greece's image abroad just a few days before the start of the Hellenic presidency of the EU Council," a foreign ministry statement quoted Deputy Prime Minister and Foreign Minister Evangelos Venizelos as saying in a phone conversation with Dold.

Police were immediately mobilized and were fighting terrorism in a coordinated and effective manner, which would promptly bring the perpetrators to justice, Venizelos said.

Deputy Foreign Minister Dimitris Kourkoulas was instructed to visit the German diplomat at his residence.

Prime Minister Antonis Samaras and Public Order Minister Nikos Dendias have also contacted the diplomat by telephone, expressing "utter condemnation" of the attack and "sentiments of friendship and support" for Dold and his family.

According to eye witnesses and CCTV footage, the gunmen fired dozens of shots with AK-47 automatic riffles at the residency.

No group has claimed responsibility for the attack. Six people were briefly detained for questioning and released without charge, police said.

It is not the first time a German diplomat's house has been attacked in Athens. In May 1999, the now disbanded Greek guerilla group "November 17" fired a rocket at a residence, again causing no injuries.

Greece has suffered from domestic terrorism for decades and attacks on political, police and business targets have escalated since the start of the debt crisis four years ago.

As Greece's biggest bailout lender, Germany is often the subject of strong criticism in the country, which is suffering through a sixth year of recession and tough austerity measures imposed as a condition of its rescue loans.