Fouad Siniora said the attack threatens the country's security and stability and constitute a violation of UN Security Council Resolution 1701.
Israel said it fired artillery shells into Lebanon in response to rockets launched from southern Lebanon. Hezbollah said it had no information about the attack.
Ibrahim al Moussavi, a spokesman for Hezbollah said that Hezbollah has nothing to do with firing rockets into northern Israel.
The Lebanese army said it found two wooden rocket launchers in the Qleileh-Mansouri area south of Tyre, the Islamic republic news agency reported.
The last rockets launched from Lebanon into Israel were fired on January 8 when a Palestinian group said it had attacked Israel in response to aggression on Gaza.