The Israeli air force attacked three buildings in Gaza early on Saturday in the first air attacks since Israel withdrew from Gaza last week after 38 years of occupation, the army said.
There were no immediate reports of casualties.
An explosion shook the Gaza City just minutes after the Israeli airstrikes.
The Israeli army said the air strikes targeted three Hamas weapons facilities, a weapons warehouse in the Jebaliya refugee camp in northern Gaza, a weapons factory in Gaza City and another weapons warehouse in Gaza City.
One missile landed in an empty field near an abandoned
workshop where Palestinian fighters used to make homemade rockets in Gaza City, causing no damage or casualties, according to Palestinian officials.
The second hit a garage outside the house of a Hamas fighter. It was not immediately clear if there were casualties in that attack.
Before leaving Gaza last week, Israeli officials said they would deal harshly with any attacks originating from the volatile coastal strip.
The air strikes came after Palestinian fighters launched 21 homemade rockets from the Gaza Strip into the Israeli town of Sderot, injuring five Israelis, one moderately and the rest lightly, the army said.
A total of 30 homemade rockets were launched from Gaza into Israel since Friday afternoon.