Netanyahu, speaking after his security cabinet on Friday approved a much-criticised plan to take control of Gaza City said he had no choice but to "complete the job" and defeat Hamas to free hostages seized from Israel.
Gaza City came under escalating Israeli air strikes on Sunday and the military said it killed a Hamas cell leader posing as an Al Jazeera journalist, but rights advocates said he had been targeted for his frontline reporting on the Gaza war and Israel's claim lacked evidence.
Anas Al Sharif, 28, was among a group of four Al Jazeera journalists and an assistant who died in a strike on a tent near Shifa Hospital in eastern Gaza City, Gaza officials and Al Jazeera said.
Al Sharif was the head of a Hamas cell and "was responsible for advancing rocket attacks against Israeli civilians and IDF (Israeli) troops," the Israeli military said in a statement, citing intelligence and documents found in Gaza as evidence.
Journalists' groups and Al Jazeera denounced the killings. The other journalists killed were Mohammed Qreiqeh, Ibrahim Zaher and Mohammed Noufal, Al Jazeera said.
Al Jazeera said Al Sharif had left a social media message to be posted in the event of his death that read, "...I never hesitated to convey the truth as it is, without distortion or misrepresentation, hoping that God would witness those who remained silent."
Al Sharif, whose X account showed more than 500,000 followers, posted on the platform minutes before his death that Israel had been intensely bombarding Gaza City for more than two hours.
Calling Al Sharif "one of Gaza's bravest journalists," Al Jazeera said the attack "is a desperate attempt to silence voices in anticipation of the occupation of Gaza."
Meanwhile Netanyahu spoke with US President Donald Trump about "Israel's plans to take control of the remaining Hamas strongholds in Gaza," the prime minister's office said.
He said the new Gaza offensive aimed to tackle two remaining Hamas strongholds in what he said was his only option because of the Palestinian group's refusal to lay down its arms. Hamas says it will not disarm unless an independent Palestinian state is established.
It was not clear when the offensive, which would be the latest in successive attempts by the Israeli military to clear the militants from Gaza City, would begin.
"The timeline that we set for the action is fairly quickly. We want, first of all, to enable safe zones to be established so the civilian population of Gaza City can move out," he said.
The city, home to a million people before the two-year-old war, would be moved into "safe zones", he said. Palestinians say these have not protected them from Israeli fire in the past.
Israel's military chief has voiced opposition to occupying the entire Gaza Strip and has warned that expanding the offensive could endanger the lives of hostages Hamas is still holding and draw its troops into protracted and deadly guerrilla warfare.
Netanyahu said his goal was not to occupy Gaza. "We want a security belt right next to our border, but we don't want to stay in Gaza. That's not our purpose," he said.
Malnutrition is widespread in the enclave due to what international aid agencies say is a deliberate plan by Israel to restrict aid. Israel rejects that allegation, blaming Hamas for the hunger among Palestinians and saying a lot of aid has been distributed.
The war began on October 7, 2023, when Hamas-led militants stormed into southern Israel and killed 1200 people and took 251 hostages. Israeli authorities say 20 of the remaining 50 hostages in Gaza are alive.
Israel's offensive since then has killed more than 61,000 Palestinians, according to health officials, and left much of the territory in ruins.
