Foreign Minister Gebran Bassil slamed the Israeli move, calling it a violation of a UN Security Council resolution that ended the 2006 war between Israel and the militant Hizballah group, the agency reported.
The wall is being built on the edge of the Lebanese border village of Kfar Kela.
Tension has been rising recently on the border between the two countries that are technically at war.
Israel last month announced the discovery of border tunnels, which it says were part of a Hizballah plot to sneak in Israel and carry out attacks.
The discovery prompted Israeli Prime Minister Binyamin Netanyahu to demand that the UN imposes sanctions on Lebanon – a request that was rejected by the body.
Israel fought a war against Iran-backed Hizballah in 2006 that was halted by a UN-brokered truce.
The conflict killed more than 1,200 Lebanese civilians, displaced over one million, and devastated infrastructure in the country.
Israel and Hizballah have since avoided major conflict, though Israel has launched multiple attacks in neighbouring Syria targeting the powerful group. ( The New Arab )