Blinken, on his second trip to Israel in a month, is due to discuss with Prime Minister Benjamin Netanyahu and other Israeli leaders concrete steps to minimise harm to civilians in besieged Gaza, where food, fuel, water and medicine are scarce.
The White House, meanwhile, said any pauses in fighting should be temporary and localised, and insisted they would not stop Israel defending itself.
"When I see a Palestinian child - a boy, a girl - pulled from the rubble of a collapsed building, that hits me in the gut as much as seeing a child from Israel or anywhere else," Blinken told reporters before leaving for Israel.
"So this is something that we have an obligation to respond to, and we will."
Newly appointed US ambassador to Israel Jacob Lew travelled with Blinken to Tel Aviv.
Gaza health authorities say at least 9061 people have been killed in Gaza since Israel launched its assault on the enclave of 2.3 million people in retaliation for deadly attacks by Hamas militants on southern Israel.
Israel says Hamas killed 1400 people, mostly civilians, and took more than 240 hostages in the attacks on October 7, the deadliest day of its 75-year-old history.
On Thursday, Netanyahu said the military had encircled Gaza City, the enclave's biggest, and was advancing.
The Israel Defence Forces on Friday said its jets, artillery and navy had struck Hamas targets overnight, killing several militants including Mustafa Dalul, a Hamas commander it said had directed combat in the Gaza Strip.
Israel has rejected UN experts' claim that Palestinians are "at grave risk of genocide".
There was no immediate confirmation from Hamas.
Mounting casualties among Palestinian civilians, along with acute shortages of basic supplies, have intensified calls by global leaders for a pause in fighting or a ceasefire.
The United Arab Emirates, one of a handful of Arab states with diplomatic ties to Israel, said on Friday it was working "relentlessly" for an immediate ceasefire, warning that the risk of regional spillover and further escalation was real.
Israel has dismissed these calls, saying it targets Hamas fighters whom it accuses of intentionally hiding among the population and civilian buildings.
The White House has also rejected calls for a ceasefire.
Blinken is also due to visit Amman to meet Jordan's Foreign Minister Ayman Safadi, who said Israel must end the war on Gaza, where he said it was committing war crimes by bombing civilians and imposing a siege.
With the conflict at the end of its fourth week, more than a third of Gaza's 35 hospitals are not functioning, with many turned into impromptu refugee camps.
More than 9000 Gazans are reported to have died in Israel's attacks.
A group of independent United Nations experts warned Palestinians there are at "grave risk of genocide" and called on Israel to agree to an immediate ceasefire.
The Israeli mission to the UN in Geneva called the special rapporteurs' comments "deplorable and deeply concerning" and blamed Hamas for the civilian deaths.
Stephane Dujarric, spokesman for the UN Secretary-General Antonio Guterres, said a determination of genocide could be made only by a relevant UN judicial body.
A military victory for Israel is unlikely to come easy.
Brigadier General Iddo Mizrahi, chief of Israel's military engineers, said troops were encountering mines and booby traps in Gaza. "Hamas has learned and prepared itself well," he said.
Israel has said it has lost 18 soldiers in the offensive. Abu Ubaida, spokesperson for the armed wing of Hamas, said in a televised speech that Israel's death toll in Gaza was much higher than the military had announced.
"Your soldiers will return in black bags," he said.
Hamas and allied Islamic Jihad fighters were emerging from tunnels to fire at tanks, then disappearing back into the network, residents said and videos from both groups showed.
The Rafah crossing from Gaza to Egypt was due to open for a third day on Friday for limited evacuations under a Qatari-brokered deal aimed at letting some foreign passport holders, their dependants and some wounded Gazans out of the enclave.
