Near the US embassy in Beirut, security forces have fired tear gas and water canons at anti-US protesters.
Demonstrators burned American and Israeli flags, with chants against President Trump and his recognition of Jerusalem as the Israeli capital.
Lebanon, which is home to about 450,000 Palestinian refugees, has condemned Trump's decision, saying it is a threat to regional stability.
The Iran-backed Lebanese Shi'ite group Hezbollah has also said it backs calls for a new Palestinian uprising against Israel.
Police in Beirut blocked off the streets leading to the US embassy in the Awkar district in the north of the city.
The head of the Lebanese Communist Party addressed the crowd.
Hanna Gharib slammed the United States as "the enemy of Palestine" and the U.S. Embassy "a symbol of imperialist aggression".
The protest is one of many that have broken out across the Arab world and in countries that are Western allies of the US.
On Saturday Arab foreign ministers meeting in Cairo urged President Trump to abandon his decision, warning that the decision would trigger violence throughout the region.