The leader of Lebanon's Hezbollah says a barrage of rockets from Syria against Israeli forces in the occupied Goal Heights last week opens up "a new phase" in the conflict, warning that Israel proper could be the next target.

Hassan Nasrallah said Monday that Israel has been informed through an international body that retaliation inside Israel will take place if it crosses "a red line" in Syria, without providing specifics.

Nasrallah said Israel's response to the barrage of rockets from Syria hit empty locations and he accused Israel of downplaying its losses from those strikes.

"If you think you can continue to hit, destroy and kill in Syria without any response, you are wrong," Nasrallah said addressing Israel. "This qualitative rocket attack establishes a completely new phase."