The protesters in al-Rashidiyeh and Ain al-Hilweh refugee camps chanted anti-Israeli slogans and raised large pictures of the late Palestinian leader Yasser Arafat and al-Aqsa, Islam's third holiest shrine.
As demonstrators burned the Israeli flag, Palestinian and Lebanese party leaders addressed the crowds, promising they would not allow the mosque to be harmed.
The protests were organized by the Palestine Liberation Organization and Lebanon's national and Islamic parties.
Justin Bieber crashes Drake Bell's album release party
Putin thinks Obama would save him if he were drowning