Soldiers fired in the air when they saw a shepherd trying to cross into the Shebaa Farms border area, the army said.
A short time later, Hizb Allah guerrillas fired rockets or missiles in the disputed border area.
There were no immediate reports of casualties from the second round of violence on the Lebanon-Israel border this month.
Israeli gunners in the Shebaa Farms also fired artillery shells at the nearby Kfar Shuba village, witnesses said.
Hizb Allah confirmed that its guerrillas attacked at least one Israeli position in the area.
Arab World 
Israeli soldiers fired at a Lebanese shepherd they suspected was trying to cross the border into Israel, sparking a cross-border clash with Lebanon's Hizb Allah resistance group, the Israeli army said.
