Several rockets landed on Monday on the Bekaa town of al-Labweh from the Syrian side of the border, the Lebanese army and the state-run National News Agency reported.
The attack did not cause any casualties, they said.
Army units deployed in the area where the rockets landed to specify their type and the exact source of the attack, the military said in its communique
The residents of al-Labweh and other Shiite towns blame Arsal for rocket fire on their villages.
Arsal is a Sunni town which is now home to 40,000 Lebanese and 52,000 Syrian refugees.
The Free Sunnis of Baalbek Brigade claimed responsibility for the rocket attack on al-Labweh.
The extremist group has previously claimed many assaults against Shiite towns and the Lebanese army.