Speaking to reporters in Rome, Austin said he raises the need to address the humanitarian needs of civilians in every call he has with his Israeli counterpart, Yoav Gallant.
In each call, Austin said he cites the need for Israel to be more precise during military operations against Palestinian group Hamas to limit civilian casualties, and cites the need to get humanitarian assistance to the civilian population.
"Failure to do that will create a generation of Palestinians that really will continue to resist cooperating with Israel in the future. So you're actually increasing the numbers of insurgents ... if you fail to do that," Austin said.
"It's a strategic imperative in my view."
Hamas-led fighters rampaged through Israeli towns on Oct. 7, 2023, killing around 1,200 people and capturing around 250 hostages, according to Israeli tallies.
Israel's subsequent bombardment of Gaza has killed more than 42,500 Palestinians, with another 10,000 unconfirmed dead thought to lie under the rubble, Gaza health authorities say.
Israel has intensified an assault on the northern edge of Gaza since killing Hamas' leader last week. Health authorities reported on Wednesday at least 20 people killed in fresh Israeli strikes, most in the north.
Aside from mass destruction, Gazans face severe shortages of food, water, fuel, medicine and proper medical care.
The United States is Israel's closest ally, and it has supported Israel's effort to go after Hamas, which is backed by Iran.
But a confidential letter from Austin and Secretary of State Antony Blinken to Israeli officials last week demanded concrete measures to address the worsening humanitarian situation in Gaza, or face potential restrictions on U.S. military aid.
Austin has declined to publicly discuss the letter.
"The ability to accomplish your goals militarily in terms of achieving the objectives and protecting civilians in the battle space ... you can do both of those things. They're not mutually exclusive," Austin said.
Israel says it has placed no restrictions on aid reaching Gaza and blames the United Nations and other international groups of failing to distribute the aid that comes into the enclave. It also says Hamas loots aid convoys, a charge the group denies.
Israel says it makes all possible efforts to avoid civilian casualties and accuses Hamas of deliberately basing its fighters in residential areas and using civilians as human shields.
Austin acknowledged Hamas' tactics of using civilians as human shields.
"Let's not kid ourselves, this is a complicated, very, very difficult battle space," Austin said.
"And so ... the Israelis need to do everything they can to be as careful as possible to protect civilians in the battle space."
