A rocket fired from Lebanese territory hit northern Israel on Monday, the army said, after overnight rocket fire from both Syria and Lebanon.
"At least one rocket fired from Lebanon hit an open area north of Nahariya," a coastal city not far from the Lebanese border, the army said in a statement.
No casualties or damage were reported, it added.
The army said it responded shortly after with artillery fire "towards the launching site" of the rocket.
A rocket fired from Syria hit the Israeli-occupied sector of the Golan Heights late Sunday, falling on open ground and causing no casualties, the army said.
And early on Monday the army said that "several rockets were fired from Lebanon at the western Galilee, one hitting an open area," with no damage reported.
The army said Israel responded with artillery fire at Syrian military posts and that "hits were identified" and that it also shelled the source of the fire from Lebanon, lodging a complaint with UN peacekeepers.
Sunday's fire was the first of its kind from Syrian territory since Israel launched a fierce air campaign against Gaza on Tuesday with the stated aim of stemming a rising tide of rocket fire by Palestinian militants.
But rockets fired from Lebanon struck northern Israel on Friday and Saturday, without causing casualties.
Military officials said they believed the attacks were carried out by a small Palestinian group in an act of solidarity with Gazan militants.