WASHINGTON -- US President Joe Biden warned Israeli Prime Minister Benjamin Netanyahu on Thursday that future US support for Israel will depend on Israel's steps to protect civilians in Gaza.

During a high-stakes phone call, Biden emphasized to Netanyahu that Israeli strikes on humanitarian workers delivering aid to Gaza and "the overall humanitarian situation" in Gaza are "unacceptable," according to a readout of the call issued by the White House.

Biden "made clear the need for Israel to announce and implement a series of specific, concrete, and measurable steps to address civilian harm, humanitarian suffering, and the safety of aid workers," said the readout.

The president, according to the readout, "made clear that US policy with respect to Gaza will be determined by our assessment of Israel's immediate action on these steps."

Biden also urged Netanyahu to both implement "an immediate ceasefire" with Hamas and "conclude a deal without delay to bring the hostages home," the readout said.

The call was the first between the two leaders after Israeli forces carried out an airstrike Monday, killing seven members of charity group World Central Kitchen (WCK) en route to distributing food to civilians in Gaza. The strike evoked international condemnation.

In a statement on Tuesday, Biden said he was "outraged and heartbroken" by the deaths of the humanitarian workers from the WCK.