Israeli warplanes watched two strikes on the Gaza Strip overnight in response to rocket fire from the Hamas-controlled Palestinian territory, an army spokesman said in a statement Sunday.

"In response to rocket fire towards Israel this weekend, the airforce targetted sites of terrorist activity in the south and the centre of the Gaza strip during the night," said the spokesman.

Palestinian militants in the Gaza Strip fired a Qassam rocket into the Eshkol region of southern Israel on Saturday morning causing no casualties, Israeli police said.

Earlier this month, the Israeli chief of staff warned MPs that repeated rocket fire from Gaza would push Israel into taking "aggressive" action in the Gaza Strip.

Low-level unrest has rumbled in and around Gaza this month but has not erupted into all-out fighting as it did on October 29-30 when tit-for-tat violence left 12 Palestinian militants and an Israeli civilian dead.

Militant groups say they are observing an Egypt-brokered truce agreement but have reserved the right to reply to any Israeli fire. Israel has said it will target any militants poised to fire rockets across the border.