Gaza officials say the fire hit Hamas observation posts near Al Maghazi and Al Bureij refugee camps in the centre of the besieged area, and the town of Khan Yunis, further south.
Israeli tanks have shelled Hamas positions in Gaza in response to continued waves of what the Israeli army said were incendiary balloons across the fence with the besieged Palestinian area.
The overnight cross-fence violence came despite the attempts of Egyptian security to end the flare-up, which has seen two weeks of rocket and fire balloon attacks from Gaza and almost nightly Israeli attacks.
"Explosive and arson balloons were launched from the Gaza Strip into Israel," said a military statement issued on Thursday.
"In response... tanks targeted military posts belonging to the Hamas terror organisation in the Gaza Strip."
Positions of the Izz Ad-din al Qassam Brigades, the military wing of Palestinian resistance group Hamas, were targeted, the Israeli army said in a statement on its Twitter account.
Gaza security officials said the fire hit Hamas observation posts near al Maghazi and Al Bureij refugee camps in the centre of the Palestinian area, and the town of Khan Yunis, further south.
There were no casualties, they said.
Terrorists launched explosive balloons from Gaza into Israel throughout the day, causing fires on land across southern Israel.— Israel Defense Forces (@IDF) August 19, 2020
In response, our tanks just targeted Hamas military posts in Gaza.
Israel and the Hamas party, which governs Gaza, have fought three wars since 2008.
In response to the balloon launches, Israel has banned fishing off Gaza's coast and closed the Karem Abu Salem goods crossing, cutting off deliveries of fuel to the territory's sole power plant.
Power had been in short supply even before the shutdown, with consumers having access to mains electricity for only around eight hours a day.
That will now be cut to just four hours a day using power supplied from the Israeli grid.