Israeli aircraft struck a Hamas facility in the southern Gaza Strip on Friday after cross-border mortar fire, the Israeli army said, as violence continued for a third day.
"In response to the ongoing attacks against Israeli forces, Israel Air Force aircraft targeted a Hamas terror infrastructure," an army statement said.
Palestinian witnesses said there were two sets of air raids, one targeting Beit Lahia in northern Gaza and the second in Khuzaa, southeast of Khan Yunis, in the south of the territory.
There were no reports of any casualties.
It was the fourth air raid on Gaza since Wednesday, when direct clashes between Hamas and Israeli forces broke out for the first time since a devastating 2014 war.
On Thursday, Israeli tank fire killed a Palestinian woman in her Gaza home.
Since the clashes broke out, Hamas and other militant groups have fired at least 10 mortar rounds across the frontier, and the Israeli air force has carried out four strikes on Gaza.
Israeli tanks stationed on the border have also fired repeatedly at what the army said were Hamas targets.
Late on Thursday afternoon, tank fire that followed a mortar attack from the Khan Yunis area killed Zeina Al-Amour, 54, according to the Nasser hospital that pronounced her death.
A 21-year-old was also wounded in shelling of the area.
The Palestinian attacks targeted Israeli forces searching along the border, and up to 100 metres (yards) inside Gaza, for tunnels crossing into southern Israel.
The army announced that it found a previously undetected tunnel on Thursday, after a first find was revealed with extensive media coverage in mid-April.
The flare-up has raised concerns over the fate of a ceasefire between Israel and Hamas, the Islamist rulers of Gaza, that has held since the 50-day war left more than 2,251 Palestinians and 73 Israelis dead.
Israeli Prime Minister Benjamin Netanyahu was to convene his security cabinet on Friday morning to discuss the latest developments, public radio reported.