During a visit to Israel, he said Prime Minister Benjamin Netanyahu had "reaffirmed his commitment" to the proposed six-week cessation of hostilities, which was also backed by a UN Security Council vote.
"Everyone has said yes, except for Hamas," Blinken said. "And if Hamas doesn't say yes, then this is clearly on them."
He then headed to neighbouring Jordan to attend an emergency summit for Gaza, alongside leaders from the Arab world and beyond, aiming to address Gaza's humanitarian crisis.
The Israeli siege has left Gaza's 2.4 million people without adequate food, clean water, medicines and fuel, pushing many to the brink of starvation. Only occasional aid shipments provide temporary relief.
"The horror must stop," UN chief Antonio Guterres told the conference, voicing his support for the truce plan first outlined by US President Joe Biden late last month.
"The speed and scale of the carnage and killing in Gaza is beyond anything in my years as secretary-general," he told the gathering on the shores of the Dead Sea.
UN humanitarian coordinator Martin Griffiths labelled the Gaza conflict a "stain on our humanity" and called for $2.5 billion in funding until year-end.
Amid diplomatic efforts to address the crisis, Israel conducted further strikes on Gaza, resulting in casualties according to hospital sources.
The Israeli army said four soldiers were killed in the southern city of Rafah on Monday in what Hamas called a booby-trap explosion.
UN Security Council vote
Israel has faced mounting international criticism over the escalating death toll in the conflict.
Health officials in Hamas-ruled Gaza reported 274 people were killed during an Israeli special forces raid on Saturday to rescue four hostages.
The UN human rights office expressed deep concern over the civilian casualties in the Nuseirat raid and said it was "deeply distressed" over the ongoing hostage situation in Gaza.
The UN Security Council on Monday endorsed a US-drafted ceasefire plan in a resolution that expressed support for the Israel-backed initiative and urged Hamas to accept it.
Hamas said it "welcomes" elements of the resolution, and also reaffirmed its willingness to engage with mediators.
However, it has also insisted on a permanent ceasefire, contrasting with Netanyahu's stance, which emphasises the return of hostages and the dismantling of Hamas.
Netanyahu suffered a setback on Sunday when Benny Gantz, a centrist former army chief, quit his war cabinet, citing the lack of a post-war governance plan for Gaza as the main reason.
During his visit, Blinken met Gantz and opposition leader Yair Lapid, both of whom have been vocal critics of the right-wing prime minister and his handling of the conflict.
Washington has also pushed for a "day-after" plan for Gaza, promoted a governance role for Hamas's rival, the Palestinian Authority, and urged steps toward a two-state solution.
Netanyahu and his far-right coalition partners reject the idea of Palestinian statehood, arguing it would endanger Israel's security and effectively "reward terrorism".
'Siege and destruction'
The Gaza war broke out after Hamas's October 7 attack resulted in the deaths of 1,194 people, mostly civilians, according to an AFP tally based on Israeli official figures.
The militants also seized 251 hostages, more than 100 of whom were released during a November truce. After special forces rescued four captives on Saturday, 116 hostages remain in Gaza, though the army says 41 of them are dead.
The Israeli army launched a devastating offensive on the Gaza Strip that has left at least 37,164 people dead, the majority of them civilians, according to the Hamas-ruled territory's health ministry.
The latest Israeli deaths in Rafah took to 298 the military's overall losses in the Gaza campaign since its ground offensive began on October 27.
In Jabaliya, Soad al-Qanou said her young child Amjad was suffering from malnutrition as aid shipments had failed to adequately address Gaza's desperate needs.
"This war has destroyed our lives and turned them upside down," she told AFP. "There is no food, no drink. There is siege and destruction everywhere."
Among aid pledges made at the Jordan meeting, the United States promised $404 million for food, water, health supplies and other aid.
Spain announced $17 million in new assistance, and Indonesia said it was ready to send medical teams, a field hospital and a hospital ship and to evacuate 1,000 patients.
Blinken, hitting back at critics of US support for Israel, noted the UN appeal for the Palestinians was only one-third funded.
"Some who have expressed great concern over the suffering of the Palestinian people in Gaza, including countries with the capacity to give a lot, have provided very little or nothing at all," Blinken said, likely referring to US adversaries China and Russia.
"It is time for everyone -- everyone -- to step up."
The United States is the largest donor to the Palestinians. It also provides Israel with $3.8 billion in annual military aid.
© Agence France-Presse
