“Democracy, however, is shielded and of course not threatened,” she said.
Journalists presenting SKAI’s morning show were broadcasting live outside the building.
Its police correspondent said the device was estimated to have contained about 5 kg of explosives and placed in a narrow alleyway close to the building.
Video footage broadcast on local media showed a cloud of smoke emerging from the building after a loud blast. Footage from within the building showed windows blown out, with desks in offices strewn with glass.
“Press freedom will not be terrorised by anyone,” New Democracy party spokeswoman Maria Spyraki told SKAI.