The UN peacekeeping mission in Lebanon reported that Israel fired into Lebanon on Tuesday morning but that there were no injuries.
UN spokeswoman Marie Okabe called it "a serious incident" and a violation of the UN Security Council resolution that ended the 34-day war between Israel and Hizbullah fighters in Lebanon in August 2006.
The UN peacekeeping mission, known as UNIFIL, "has protested to the Israel Defense Force," she said.
The incident took place in the area of El Adeisse near the UN-drawn Blue Line along the Israeli-Lebanese border, Okabe said.
A UNIFIL team visited the location and found that at least two rifle shots impacted a wall in Lebanon approximately 50 meters (yards) from the Blue Line, she said.