At least five people were killed and another 80 wounded when twin explosions struck a Beirut neighborhood housing Iranian government entities, the Daily Star newspaper in Lebanon reported.
Iranian Foreign Ministry spokeswoman Marziyeh Afkham said mercenaries used by the Israeli government were behind the attack.
"There is no doubt that the agents behind the terrorist action in Beirut are enemies of Lebanon's stability, security and unity and are the hirelings of the Zionist regime who have been disappointed by the formation of a new government in the country," she said in a statement published by Iran's semiofficial Fars News Agency.
Hezbollah lawmakers were appointed to two of the eight ministries awarded to the March 8 political coalition in Lebanon. Sixteen other seats were divided equally between the March 14 coalition, backed by Western powers, and moderates hand-picked by key political figures.
Hezbollah counts Iran as its main backer. The Shiite movement's role in support of pro-government forces in Syria sparked reprisal attacks in parts of Beirut, Lebanese security officials say.
Hezbollah said it needs to maintain a defensive posture in Lebanon to protect the country from Israel, its arch foe.
The Abdullah Azzam Brigades, which has links to al-Qaida, a Sunni group, claimed responsibility for bombings, the Daily Star reported.