(NewsNation) — U.S. President Joe Biden told Israeli Prime Minister Benjamin Netanyahu that U.S. policy regarding Israel will be determined by whether it implements concrete steps to address “civilian harm, humanitarian suffering, and the safety of aid workers” in Gaza.

Thursday marked the two’s first phone call following Israeli airstrikes that killed seven food aid workers in Gaza, which Biden called “unacceptable.”

For the U.S., steps Israel should take are a dramatic increase in getting additional aid crossings opened up and a reduction in violence on civilians and aid workers, National Security Communications Adviser John Kirby said in a press briefing.

Netanyahu, meanwhile, reiterated his thanks to the United States while talking to Biden.

While calling Netanyahu, Biden said an “immediate cease-fire” is needed, and urged him to empower negotiators to come up with a deal that would allow one in exchange for Hamas’ release of the hostages it took during its Oct. 7 assault on Israel.

Blinken told reporters some details of the call at a press conference in Brussels, where he said, “This week’s horrific attack on the World Central Kitchen was not the first such incident.”

“It must be the last,” he said.

Meanwhile, Secretary of Defense Lloyd Austin spoke with his Israeli counterpart on Wednesday night.

During Monday’s strike, NewsNation partner The Hill reports, three vehicles were targeted in three separate strikes — even after the group coordinated its movements with Israel’s military, according to a WCK press release.

Those who died included three British citizens, Polish and Australian nationals, a Canadian-American dual national and a Palestinian. 

Around 200 humanitarian aid workers have already been killed during this conflict — but these seven deaths are causing international outrage.

Biden released a statement following the strike criticizing Israel’s government for not doing enough to protect those trying to deliver aid to civilians.

José Andrés, the chef who founded World Central Kitchen, said the strikes were deliberate. He is now calling for an independent investigation outside of the one Israel has said it will conduct.

The IDF, meanwhile, claims the attack was a “grave mistake,” with Chief of the General Staff Herzi Halevi saying, “It shouldn’t have happened.”

However, Andrés says: “This was not just a bad luck situation where ‘oops we dropped the bomb in the wrong place.'”

Food aid workers in Gaza were targeted “systematically, car by car,” he told Reuters in an interview Wednesday.

So far, the White House says they still plan to support Israel with weapons, despite growing calls for that to come to an end, as well as for a broader cease-fire.

More than 33,000 Palestinians have been killed as Israel has conducted its ground offensive and bombardment of Gaza, with more than 75,600 wounded, according to the Health Ministry in Gaza.

Among those, women and children make up two-thirds of the dead. Much of the population in northern Gaza is on the brink of starvation, the United Nations says. A top UN court concluded in January there’s a “plausible risk of genocide” in Gaza, which Israel denies.

One of Biden’s closest allies in the Senate, Delaware’s Chris Coons, urged Thursday for the U.S. to put conditions on military aid to Israel if it decides to go into the city of Rafah, where many are sheltering in Gaza after being displaced, without plans to protect civilians or provide aid.

After the call, though, some Republican lawmakers criticized Biden. Rep. Brian Mast, of Michigan, said the president is trying to “boost his poll numbers.”

However, a couple of Democrats took to X to say that they wanted to see more humanitarian aid for Palestinian civilians, such as Rep. Jim Clyburn of South Carolina.

“Far too many innocent civilians have lost their lives in this conflict,” Clyburn wrote.

Joe Khalil contributed to this report.