The air strikes came after three Grad rockets were fired from Gaza into the Ashdod and Bnei Aish areas shortly before midnight Wednesday, The Jerusalem Post reported.
The rockets landed in open territories and no injuries were reported.
Sirens could be heard in in Yavne, Gedera, Rehovot, Nes Ziona and Ashdod, the Post said.
The rocket attacks were the first since the deal that freed Israeli soldier Gilad Shalit last week in the exchange for 1,027 Palestinian prisoners.
Haaretz said the Gaza has been mostly calm, with a few rocket launches, since a terrorist attack on the Egyptian border that killed eight people Aug. 18.
Haaretz said it was unclear which Palestinian group fired a rocket that landed in a field between Ashdod and Gedera.
A loud explosion, heard clearly throughout Ashdod, indicates it had a large warhead.
Haaretz said Israeli intelligence officials believed Hamas, which is trying to gain leverage after getting prisoners freed in the Shalit swap, had little incentive to launch such an attack, which could escalate conflict, and a small faction may have defied Hamas and fired the rocket.
Israeli defense officials expressed concern that Hamas has recently smuggled into Gaza advanced Russian missiles looted from a Libyan warehouse.
The defense officials say the ground-to-air missiles could restrict the Israeli air force's freedom to fly over Gaza and could be used to target civilian aircraft in Eilat.