The United Nations Interim Force in Lebanon said its peacekeepers were fired upon three times on Sunday, "likely by non-state armed groups" in the country's south.
The incident came two days after a different UN position was hit by fire that official Lebanese media blamed on Israel, with UNIFIL saying it was investigating.
"Today, UNIFIL peacekeepers were fired upon, likely by non-state armed groups, on three separate occasions while conducting patrols around their bases" in south Lebanon, the force said in a statement.
In one of the locations, the fire struck "as close as five meters from the peacekeepers", it added.
"Two patrols returned fire in self-defense and after brief exchanges, the patrols resumed their planned activities. No peacekeeper was injured," the statement said.
"We strongly remind all actors of their obligations under international law to ensure the safety and security of UN personnel at all times."
Lebanon was drawn into the broader Middle East war on March 2, when the Tehran-backed group Hezbollah attacked Israel in retaliation for the killing of Iranian supreme leader Ali Khamenei in US-Israeli strikes.
Israel has since launched waves of air strikes on its northern neighbor and deployed troop into border areas, while Hezbollah has launched rockets and missiles towards Israeli territory and troops.
Lebanese state media said that Israeli fire hit a UNIFIL base in southern Lebanon on Friday.
UNIFIL spokesperson Kandice Ardiel said the position was hit "likely by heavy machine gun fire", without identifying the source, and said an investigation had been launched into the incident, which left one peacekeeper lightly wounded.
Earlier this month, three peacekeepers serving with a Ghanaian contingent were wounded in south Lebanon, with Lebanese President Joseph Aoun accusing Israel of being responsible and UNIFIL saying it would investigate.
On Saturday, during a visit to Beirut, UN chief Antonio Guterres said attacks against peacekeepers and their positions were "completely unacceptable and... may constitute war crimes".
UNIFIL has acted as a buffer between Israel and Lebanon since 1978. Its mission concludes at the end of this year.
