The Israeli military hit three Hamas targets in Gaza on Friday after new protests along the border led to violence in which 28 Palestinians were wounded.
Palestinian protesters on Friday launched fire balloons into Israel, blackening large patches of vegetation on the other side of the border.
Palestinian health officials said Israeli fire wounded 28 Palestinians during protests along the barrier.
Palestinian activists for the past week have been protesting next to the fence separating Gaza and Israel.
The protests have turned violent, with demonstrators hurling explosives towards Israeli troops, and soldiers responding with tear gas and live fire.
Hamas, which has ruled Gaza since 2007, said youths organised the protests in response to Israeli provocations.
On September 15, Israel launched its first air strike on Gaza since early July. Hamas sites were the targets.
In Friday's strikes, an Israeli drone hit two Hamas positions and a tank struck a third, the military said.
It said shots had been fired at its troops from near one of the targets, without causing any casualties.
The latest casualties on the Palestinian side take the number of wounded in the protests to 88, Health Ministry figures have shown.
One protester was killed by Israeli fire while five died in an explosion that witnesses said may have been the result of the premature explosion of a hand grenade.
The violence in Gaza follows an Israeli announcement late on Sunday that it would keep the Erez border crossing closed.
Thousands of Palestinian workers from Gaza are prevented from entering Israel by the closure, which an Israeli NGO, Gisha, condemned as "collective punishment".