Plumes of smoke were seen off the Tel Aviv coast on Saturday following the apparent launch of long-range rockets from Gaza by Hamas.
Residents of the city also reported hearing loud explosions. Police said there were no casualties or damage.
There was no immediate claim of responsibility.
Hamas, which rules the Palestinian enclave, has occasionally test fired rockets, launching them towards the sea.
However, the Hamas-affiliated Paltimes news website said that Saturday's launch was not deliberate and was probably caused by a malfunction.
Israeli Deputy Defence Minister Alon Schuster said that the military was not expecting an escalation but said "we will not be Hamas's punching bag".
The Israel-Gaza frontier has been largely quiet since an 11-day war last May. However, an Israeli defence contractor was wounded by gunfire from Gaza on Wednesday. The shots drew Israeli tank fire, which injured three Palestinians.
