Video posted on WhatsApp by Netanyahu's right-wing Likud party showed him returning to the stage after the all-clear and saying that Hamas was scared of him winning next general election.
A source familiar with the investigation said a Salafist movement in Gaza, which is run by Islamist movement Hamas, that sympathises with the Islamic State jihadist group was suspected.
It was the latest in a series of violent incidents along the Gaza border in the run-up to a September 17 Israeli general election.
On Friday Palestinians in Gaza fired a rocket at Sderot, in what the army said was the first such attack since July 12.
Balloons with attached incendiary devices are flown over the Gaza border by Palestinian demonstrators seeking to start fires in nearby Israeli farmland.
The ministry said three people, including a pregnant woman, were killed in northern Gaza and two in southern Gaza, raising an earlier toll of seven.
Israel said around 450 rockets or mortars had been fired from the Palestinian enclave run by Hamas since Saturday, and it responded with waves of air and tank strikes.
On Thursday, Israel said its aircraft struck a Hamas military compound after balloons carrying firebombs and explosives were launched across the border.
The Erez crossing for people and the Kerem Shalom crossing for goods reopened Sunday morning, a spokeswoman for COGAT, the defence ministry unit that oversees the crossings, told the media.
Calm prevailed throughout Tuesday, with Hamas claiming Egypt had brokered a ceasefire, but as night fell Israel said a projectile was fired from Gaza around 8:00 pm
Several airstrikes rocked Gaza with one resulting in an explosion that destroyed the office of Hamas leader Ismail Haniyeh.
Israel's army had earlier reported a rocket fired from the Gaza Strip at Israel but a spokeswoman could not comment further for now.
There were no reports of damage or casualties, the Israeli army said, and no group in Gaza immediately claimed the attack, but in a statement, Hamas's military wing denied responsibility for the attac
The cancellation, the first of its kind in a year, came after Israel said its aircraft struck dozens of Hamas targets in Gaza overnight in response to rockets fired from the enclave, including at Tel
The zoo in the war-battered Palestinian enclave is promoting itself as offering the chance to play with the 14-month-old declawed lioness, which is supposed to be placid enough to meet visitors.