US Secretary of State Antony Blinken says the United States cannot support a major Israeli military operation in the southern Gaza city of Rafah without an effective plan to protect civilians.

Blinken made the remarks after meeting with Israeli Prime Minister Benjamin Netanyahu in Israel on Wednesday. They discussed ongoing negotiations for a ceasefire in the Gaza Strip and the release of hostages held by Hamas.

Blinken told reporters that the Israeli government has not presented an effective humanitarian plan. He added that there are other ways of dealing with Hamas that do not involve a large-scale operation in Rafah.

Netanyahu earlier said he would press ahead with an offensive in Rafah with or without a deal.

Blinken said there is an agreement between the US and Israel that if a deal on a ceasefire and hostages is reached, "we'll look for ways to build on that and have something that's sustainable over time."

He reiterated his call for Hamas to accept a truce.

Earlier in the day, Blinken visited the Kerem Shalom crossing at the border with Gaza, through which trucks enter the enclave to deliver humanitarian supplies.

White House Press Secretary Karine Jean-Pierre told reporters on Wednesday that a ceasefire as part of a hostage deal should ''happen immediately."

She noted that Hamas has not yet responded.

Jean-Pierre said Washington had made clear to its partners in the region that all efforts need to be made to convince Hamas to accept the proposal immediately.