Two people died in clashes yesterday and another two were killed early today in the northern port city of Tripoli, the official said, adding that scores more were wounded, including 16 in the past two days alone.
Sunni and Alawite gunmen have been fighting since Monday in the Bab al-Tebbaneh and Jabal Mohsen districts of Tripoli, Lebanon's second city.
Until yesterday, six Sunnis and three Alawites had been killed in the latest bout of fighting which broke out on Monday.
Tripoli is home to 200,000 people, 80 percent of whom are Sunni Muslims, 6-7 percent Alawites and the rest Christians.
Acting Prime Minister Najib Mikati said on yesterday that "security forces will take every step to put an end to the violence and chaos" in the city. "They will be strict and impartial."
A security official said the army had separated the two sides and pushed them back.
The fighting broke out on Monday as a Lebanese private television aired an interview with the Syrian president, in which he said the time is not ripe for a peace conference to try to resolve the 31-month conflict and said he was ready to run for re-election in 2014.
Lebanon is deeply divided into pro- and anti-Damascus camps.
The division has widened since Lebanese Shiite movement Hezbollah admitted in May it was sending fighters into Syria to support Assad's troops.
Small radical Sunni organisations have also sent men across the border to fight alongside rebels.
Lebanon was dominated politically and militarily by Damascus for 30 years until 2005.