Ehud Barak said the situation on the Israel- Gaza Strip border was "unacceptable" after a barrage of rocket attacks.
The Israeli defense minister toured the border town of Sderot on Friday after 16 rockets were fired from Gaza, including five long-range rockets that reached the environs of Ashkelon.
Israel retaliated with an air-launched missile that woundeed two Palestinian gunmen.
The intensification came a day after Israeli troops killed four Palestinian militants that the army said were trying to infiltrate from Gaza. Gaza’s Hamas rulers pledged retaliation, and the barrage of rockets Friday injured at least one Israeli, an 80-year-old woman.
Israel and Hamas have observed a fragile Egyptian-brokered ceasefire since the summer.
"If Hamas wants a ceasefire, we will consider it," Barak said, "but the situation as it is is unacceptable."