Around 20 Katyusha rockets and mortar rounds were fired at positions in Ramta and Sammaqiyeh on Wednesday, Israeli security sources said.
Hizb Allah artillery also fired on Israeli army positions at Aaamfit, on the Israeli-occupied Golan Heights.
Lebanese police said Israeli artillery responded to the attacks, firing some 50 rounds on hills around the towns of Kfarshuba and Shebaa, adding that there are no immediate reports of casualties.
Israeli warplanes also bombed the outskirts of a south Lebanese border village.
Witnesses said smoke billowed from the hills outside Kfar Shouba after the planes fired at least two missiles. There is no immediate word on casualties from the raid.
The Hizb Allah attacks come as Israeli forces have been reinforcing fortifications along the frontier between the Shebaa Farms and Lebanon, including installation of new barbed-wire barriers and surveillance cameras.
Hizb Allah's leader says Israel
is occupying the Shebaa Farms
The last attack was on 21 May, when Hizb Allah fighters fired on troops in the sector in response to Israeli fire that damaged five houses in Shebaa.
The small mountainous Shebaa Farms area lies at the convergence of the Israeli, Lebanese and Syrian borders.
It was captured from Syria in the 1967 Arab-Israeli war and is now claimed by Lebanon, with Damascus's approval.