Israeli aircraft hit a Hamas compound in the southern Gaza Strip on Saturday, after Palestinians there fired a rocket into Israel, the Israeli army said.
"In response to the projectile fired at southern Israel...fighter jets struck a Hamas compound composed of two military structures," the army statement said.
There were no reports of casualties on either side.
It was the second exchange in 24 hours, after the air force hit a Hamas position in Gaza early Friday in response to a rocket being fired from the Palestinian enclave the night before.
Such rockets are usually fired not by Hamas, the Islamist group that controls the territory, but by fringe radical groups.
Israel holds Hamas, with which it has fought three wars since 2008, responsible for any fire coming from Gaza.