The embassy was evacuated, and the package bomb was defused without injuries to anyone.
The incident follows similar incidents last Friday when package bombs went off at the Swiss and Chilean embassies. At least one of the devices contained an iron bolt that shot into the chest of the Chilean employee. That man also risked losing the sight in his eye; both he and the Swiss victim had serious injuries to their hands and arms, hospital officials said.
The bombings are blamed on international anarchists.
"Having been done in the same way, we can just hypothesize that there is the same hand behind it," Greek Ambassador Michalis Kambanis said at the embassy, although he added that he knew of no specific claim of responsibility.
Police also responded to suspicious packages at the Venezuela, Monaco and Denmark embassies, but those were all false alarms.
Police had told all embassies in the capital to be on alert after the package bombs on Thursday; Monday was the first day of business after the Christmas holiday. Some embassies chose to remain closed as a precaution: Sweden's Foreign Ministry said no packages had been found at its embassy in Rome but that it was closed Monday "for security measures."
An Italian group calling itself the Informal Anarchist Federation claimed responsibility for Thursday's blasts. News reports said that a claim found at one of the embassies cited the name of Lambros Fountas, a Greek anarchist who was killed in a shootout with police in March.
The Associated Press contributed to this report.