Demonstrators attacked the headquarters of a Lebanese television channel in Beirut on Tuesday night, protesting against a broadcast they said was insulting to Lebanese Shiite cleric Imam Musa al-Sadr.
Around 300 people, some carrying flags of Lebanon's Shiite Amal Movement, tried to storm the headquarters of Lebanese channel al-Jadeed, throwing fireworks, stones and eggs at the building.
Scores of police and troops rushed to the area. One policeman was injured and the army later broke up the protest.
Sadr, the founder of the Amal Movement, disappeared after traveling to Libya in 1978 and is presumed dead. Lebanese media said the Tuesday demonstration had been in reaction to a broadcast comedy sketch that referred to the disappearance.
Protesters broke windows, shouted insults at the channel's owner, and chanted "Here we are Nabih", referring to Parliament Speaker Nabih Berri, head of the Amal Movement.
A security source described the attack as serious but said the army was in control of the situation. An al-Jadeed correspondent said on live television that a fire had erupted in the building, ignited by the fireworks.
Various Lebanese political parties denounced the attack, and President Michel Aoun called the minister of defense and other officials to restore calm, al-Jadeed said.