Two hand grenades thrown Thursday night at the office of Michel Aoun - a Hezbollah-allied politician - damaged property but did not injure anyone, Lebanon's National News Agency reported.
The attack took place in Beit Habab, about 16 miles outside Beirut, at the headquarters of the Free Party Movement, a Christian party led by Aoun.
Lebanese security forces investigating the incident have yet to determine if it was related to the government's collapse on Wednesday. According to eyewitnesses, only one of the grenades exploded.
Hezbollah's resignation from the cabinet on Wednesday - while Lebanese Prime Minister Sa'ad Hariri was in Washington for meetings with President Barack Obama - brought down the 14-month-old unity coalition.
The Shi'ite group had threatened to quit the government unless Hariri convened the cabinet to discuss pending indictments by a U.N. tribunal against members of Hezbollah for the 2005 assassination of former Prime Minister Rafik Hariri, Sa'ad's father.
Shortly before the incident, Hezbollah spiritual leader and general secretary Sheikh Hassan Nasrallah said the group's resignation would not lead to civil war between Lebanon's Shi'ite and Sunni Muslims.
Israel's Channel 10, quoting al-Jazeera, reported that Nasrallah blamed the prime minister for the political unrest in the country and advised him not to return to Lebanon.
Just over a year ago, Hariri brought Hezbollah into the unity coalition with 10 mandates in the 30-member cabinet and parliamentary veto power.
Hariri left Washington for Paris, where he met with French President Nicolas Sarkozy. From there, he travels to Turkey to meet with Foreign Minister Ahmet Davutoglu, followed by Syria, before returning home to Beirut.