Blinken and Israeli Prime Minister Benjamin Netanyahu met in Jerusalem for two-and-a-half hours, after which Israel repeated that the Rafah operation would go ahead despite the U.S. position and a U.N. warning that it would lead to "tragedy".
"We cannot, will not support a major military operation in Rafah absent an effective plan to make sure that civilians are not harmed and no, we've not seen such a plan," Blinken told reporters.
"There are other ways, and in our judgment better ways, of dealing with the ... ongoing challenge of Hamas that does not require a major military operation in Rafah," he said, adding that it was the subject of ongoing talks with Israeli officials.
An Israeli government spokesperson said Israel remained determined to destroy the remaining Hamas fighting formations.
"When it comes to Rafah - we are committed to remove the last four of five Hamas battalions in Rafah - we are sharing our plans with Secretary of State Blinken," the spokesperson told a regular briefing.
Israel is the final stop on the top U.S. diplomat's Middle East tour, his seventh visit to the region which was plunged into conflict last October when Hamas attacked southern Israel. It has largely focused on efforts to improve humanitarian conditions in Gaza.
Blinken spoke at Israel's main port, Ashdod, and praised "meaningful progress" in recent weeks on humanitarian access, including by allowing flour for Gaza to flow through the port, as well as by opening up new border crossings.
"The progress is real but given the need, given the immense need in Gaza, it needs to be accelerated, it needs to be sustained," he said.
Blinken asked Israel's government to take a set of specific steps to facilitate aid to Gaza, where nearly half the population are suffering catastrophic hunger, he said.
The United States is Israel's main diplomatic supporter and weapons supplier. Blinken's visit comes about a month after U.S. President Joe Biden issued a stark warning that Washington's policy could shift if Israel fails to take steps to address civilian harm, humanitarian suffering and the safety of aid workers.
Blinken also urged Hamas to accept a truce deal proposed by Egyptian mediators which would see 33 hostages released in exchange for a larger number of Palestinian prisoners and a halt to the fighting, with the possibility of further steps towards a comprehensive deal later.
"Israel has made very important compromises," he said. "There's no time for further haggling. The deal is there. They (Hamas) should take it."
A senior official for Hamas said it was still studying the proposed deal but said Israel was the real obstacle.
"Blinken's comments contradict reality," Sami Abu Zuhri told Reuters.
Israel is holding off sending a delegation to Cairo for follow-up truce talks, pending a response from Hamas' leader in Gaza, Yahya Sinwar, an Israeli official told Reuters.
ASSAULT ON RAFAH
U.N. aid chief Martin Griffiths said on Tuesday that an Israeli ground operation in Rafah was "on the immediate horizon." In a statement, he said Israeli improvements to aid access in Gaza "cannot be used to prepare for or justify a full-blown military assault on Rafah."
Netanyahu has insisted the operation will go ahead, whatever the outcome of the talks, and Israeli media reported on Wednesday that he was still refusing to accept Hamas' central demand that any deal would have to include a permanent ceasefire and a withdrawal of Israeli troops.
Ynet news site, citing the Prime Minister's Office, said Netanyahu told Blinken a Rafah operation "was not contingent on anything" and that he rejected any truce proposals that would end the Gaza war.
While facing international calls to hold off on any Rafah offensive, Netanyahu has faced pressure from the religious nationalist partners he depends on for the survival of his coalition government to press ahead. Israel has described Rafah as a last bastion of Hamas, which it has vowed to eliminate.
En route to a visit to Kerem Shalom, one of the main crossing points for aid into Gaza, Blinken made a brief stop at Kibbutz Nir Oz in southern Israel, where Hamas attacked on Oct.7, killing dozens of residents and kidnapping others. Blinken visited the heavily damaged home of an American-Israeli family, all of whom, including five-year old twins, were killed in the assault.
Hamas killed 1,200 people and abducted 253 in the assault, according to Israeli tallies. The hostages are mostly Israeli but include some foreign nationals.
In response, Israel has overrun Gaza, killing more than 34,000 Palestinians, local health authorities say, in a bombardment that has reduced much of the enclave to a wasteland.
More than one million people face famine after six months of war, the United Nations has said.
As night fell on Wednesday, Israeli planes and tanks pounded several areas across Gaza, residents and Hamas media said.
Medics in Gaza said at least 27 Palestinians were killed in strikes on Wednesday, with others likely hurt or killed in areas they were unable to reach.
