The UN Interim Force in Lebanon (UNIFIL) said on Thursday that unknown people fired approximately 30 shots in the direction of peacekeepers.
The incident happened Thursday morning when a UNIFIL patrol near Qallawiyah noticed a cache of ammunition near the roadway, a UNIFIL statement said.
After informing the Lebanese Armed Forces of the discovery, peacekeepers continued on their planned route, it added.
"A short while later, they got out of their vehicle to remove some debris from the roadway. When getting back into their vehicles, two or three unknown people fired approximately 30 shots in their direction.
"The peacekeepers fired back from their vehicles and moved to safety," it said, adding it is "unclear" if the discovery of the weapons cache and the attack are directly linked.
UNIFIL said no one was hurt and there was no damage to the vehicles, and it launched an investigation.
"Peacekeepers cannot be targeted, ever. Firing toward them is a flagrant violation of international law and of resolution 1701," it said, adding it requested the Lebanese authorities undertake "a full and complete" investigation into the incident.
On Wednesday, the UN Security Council condemned attacks on the UNIFIL in recent weeks, calling on all parties to respect the safety of members of that force.
"They (the members of the Security Council) urged all parties to take all measures to respect the safety and security of UNIFIL personnel and premises. They recalled that peacekeepers must never be the target of an attack," a council statement said.