The latest bout of violence in the northern city of Tripoli, which has left nine people dead and several dozen more wounded, began after the authorities arrested Shadi el Mawlawi.
Islamic groups in the north of Lebanon have closed one of the city's main squares in protest against Mawlawi's arrest, who is now facing terrorism charges.
The city is home to a large Alawite minority, which is the sect that Syrian president Bashar al Assad belongs to, as well as a Sunni majority, who support the Syrian opposition.
Lebanese troops deployed on Tuesday in sectors of Tripoli affected by clashes. They are said to be on Syria Street, the fontline of the fighting between the residents of Bab el Tabbaneh and Jabal Mohsen.
"Hostilities have ceased in Tripoli," Najib Mikati, Lebanese prime minister, said on Tuesday in Beirut, adding that "the past 48 hours have been difficult."
Mikati said he had met political officials and Islamist leaders to discuss the crisis. "We reached an understanding on a number of issues," including a ceasefire, he said.
Al Jazeera's Zeina Khodr reports from Tripoli, Lebanon.