The Israeli military said it conducted artillery and air strikes in southern Lebanon, alleging that it targeted Hezbollah fighters and weapons sites.
It said the strikes hit rocket launchers and storage facilities as tensions have risen in recent days despite the truce.
Earlier, Hezbollah said it attacked Israeli troops inside Lebanon as well as a rescue force sent to evacuate them.
The US-mediated ceasefire, in place since April 16 and extended to mid-May, has reduced hostilities but both sides continue to accuse each other of violations.