GAZA CITY - Hamas's leader in Gaza said Friday his movement did not seek war with Israel but would resist incursions into the Palestinian enclave, following the worst cross-border violence since the 2014 war.

Three days of mortar and tank fire between Israel and Palestinian militants, as well as Israeli air strikes, have raised concerns of a new conflict in the Hamas-run territory.

Ismail Haniyeh accused Israeli forces of intruding nearly 200 metres (yards) into Gazan territory.

"We are not calling for a new war, but we will not under any circumstances accept these incursions," he said in a Friday prayer sermon in the Gaza Strip.

Earlier in the day Israeli aircraft carried out their fourth air raid on the Palestinian enclave since Wednesday, attacking sites at Beit Lahiya in northern Gaza and near Khan Yunis in the south of the territory, witnesses said.

There were no reports of any casualties.

The Israeli army confirmed only one strike, saying it was a reaction to cross-border mortar fire.

"In response to the ongoing attacks against Israeli forces, Israel Air Force aircraft targeted a Hamas terror infrastructure," an army statement said.

Since Wednesday, Hamas and other fighter groups have fired at least 12 mortar rounds across the frontier, while Israeli tanks stationed on the border have fired repeatedly at what the army said were Hamas targets.

The Palestinian fire targeted Israeli forces searching along the border, and short distances inside Gaza, for infiltration tunnels leading into southern Israel - among the most feared weapons of Hamas fighters during the 2014 conflict.

On Thursday, Zeina Al-Amour, a 54-year-old Palestinian woman, became the first fatality of the flare-up after Israeli tank fire hit her home, medics said.

The violence has raised concerns for a ceasefire between Israel and Hamas that has held since the 50-day war in 2014 left 2,251 Palestinians and 73 Israelis dead.

On both sides of the border, residents said they were living in fear of a wider conflict.

"In the night there is the sound of mortars, bombs, planes," said Jehan Berman, a resident of kibbutz Kerem Shalom which is only 40 metres (yards) from the border with Gaza. "We're tired. We're still recovering from the last war and the next one is already at our door," he said.

Kerem Shalom is close to where the army has uncovered two Hamas tunnels, allegedly stretching into Israeli territory, in recent weeks, the most recent discovery coming on Thursday.

Destruction of the tunnels became one of Israel's primary goals during the 2014 war, with more than 30 eliminated, according to the army.

Since the conflict, Hamas has continued to build what it calls "resistance tunnels."

Citing Hamas activities, Israel maintains a tight blockade on Gaza which human rights groups say is collective punishment against its more than 1.8 million residents.

Ali al-Moghrabi, 40, a tailor from Gaza City's Al-Hanan Zeitun neighbourhood which was bombed on Thursday, said he still had not recovered from the last conflict.

"We do not want war, but the occupier (Israel) never stops," he said. "People are already suffering from the blockade, unemployment and poverty."

Hanane Akkaoui, a 53-year-old mother, said she was scared for her children.

"Bombs don't differentiate between civilians and resistance (fighters)," she said.

Hamas has accused Israeli soldiers of incursions into Gazan territory in recent days, saying this constitutes a violation of the 2014 truce.

The Israeli army admits it has operated inside Palestinian territory but said it was within 100 metres of the border, where it says it has operated since the 2014 war.

Israeli Prime Minister Benjamin Netanyahu convened his security cabinet on Friday to discuss the latest developments, public radio reported.

A spokesman for Netanyahu's office said only that "an update was provided by security officals on IDF (Israel Defence Forces) activities of the past few days and the exposure of the tunnel."

Army spokesman Peter Lerner said on Thursday that Israel had "no interest whatsoever" in a military escalation but added that it would continue to act against Hamas as "it continues to breach Israeli sovereignty and build tunnels."

Israeli media reported on Friday that a pending report on the conduct of the 2014 war is set to be highly critical of Netanyahu, Defence Minister Moshe Yaalon and others.

Yediot Aharonot newspaper said the report by the state comptroller, a national watchdog, would conclude that during the conflict "the security establishment did not have a comprehensive plan for dealing with Hamas's offensive tunnels."