As reported by Censor.NET, this was announced by Reuters.
The explosion smashed windows but caused no injuries.
The blast, which police believe was carried out by domestic guerrilla groups, is the first such incident since leftist Prime Minister Alexis Tsipras came to power in January.
Attacks against banks, politicians and business people are not uncommon in Greece, which has a long history of political violence and has been mired in its worst economic crisis in decades.
The device, triggered by a timer and placed in a backpack near the entrance of the Hellenic Business Federation offices, went off around 3:30 a.m. (0130 GMT). An anonymous caller warned a newspaper some 30 minutes earlier, a police official said on condition of anonymity.
Witnesses said glass from smashed windows was strewn across the streets in one of the busiest parts of central Athens, a stone's throw from parliament in Syntagma Square that is lined with cafes, banks and shops.
Photos by Khaleej Times