Thousands of Palestinians killed in Israel’s attacks on Gaza over the past three weeks “did not deserve to die”, according to the US national security adviser, in a marked softening of the Biden administration’s hardline support of Israel.

In an interview with ABC News on Sunday, Jake Sullivan, the White House’s chief security adviser, said Hamas is “hiding” behind civilians but that doesn’t lessen Israel’s “responsibility under international humanitarian law and the laws in war to do all in their power to protect the civilian population”.

“There have been deaths of thousands of Palestinian civilians in this conflict and that is an absolute tragedy … Those people did not deserve to die. Those people deserve to live lives of peace and safety and dignity,” Sullivan told ABC’s This Week.

At least 8,000 Palestinians including more than 3,300 children and more than 2,000 women have been killed by Israeli’s military bombardment of Gaza, according to Gaza’s health ministry. The toll is expected to rise as Israel continues with its ground offensive – in addition to ongoing aerial attacks.

Israel’s current offensives were launched in retaliation for the surprise cross-border attack on 7 October in which Hamas, which has run Gaza since 2007, killed about 1,400 people in Israel and took more than 200 hostages.

“Israel has a right – indeed a duty – to defend itself against terrorists. Israel also has a responsibility to distinguish between terrorists and ordinary civilians,” said Sullivan.

Sullivan’s remarks come after another weekend of mass protests across the country demanding an immediate ceasefire and an end to America’s financial and political support for Israel. In New York, thousands of people occupied Grand Central station during the Friday night rush hour in an act of civil disobedience organized by progressive groups Jewish Voices for Peace and IfNotNow.

Hundreds of protesters were arrested inside Grand Central amid shouts of ‘Let Gaza live’ and ‘never again for anyone, never again is now’ – a slogan associated with the lessons of the Holocaust and other genocides.

Sullivan’s remarks on civilian deaths come after Biden cast doubt on the veracity of the Palestinian death toll reported daily by the Gaza health ministry.

“I have no notion that the Palestinians are telling the truth about how many people are killed. I’m sure innocents have been killed, and it’s the price of waging a war,” the US president said last week. “But I have no confidence in the number that the Palestinians are using.”

UN agencies and Human Rights Watch have over many years checked – and verified – the health authority’s figures, finding no major discrepancies.

Biden’s remarks triggered widespread anger, with the Council on American-Islamic Relations calling on the president to apologize for his “shocking and dehumanising” remarks. There is growing anger among progressives including Arab Americans, whose vote was crucial to Biden’s election win in 2020.

Last week, two American hostages were released by Hamas but Israel says that more than 200 people from dozens of countries remain captive. Securing the safe passage of Americans remains the Biden government’s priority, Sullivan told news programs on Sunday.

Asked about ​​the status of Americans and other foreigners trapped at the Rafah crossing in Gaza by CNN’s Jake Tapper, Sullivan said: “Hamas has been preventing their departure and is making their demands … this is an equal priority for us as is to get the hostages out.

Around 2.3 million Palestinians are trapped without food, water and medicines in Gaza, which even before this bloody conflict has been described by international human rights groups as an “apartheid state” and “open air prison”.

Sullivan has come under criticism for an essay published in the Foreign Affairs magazine just five days before Hamas’s surprise and shocking attack on Israel, in which he wrote in the face of “serious” frictions, “we have de-escalated crises in Gaza”.

The weekend bombardment – described by Gaza residents as the most intense of the war – was carried out in a blackout after Israel shut down communications in the territory late Friday. Some communications was restored to much of Gaza early Sunday.

Protesters from across the US are expected to descend on the capital next Saturday, in what’s expected to be the largest pro-Palestinian protest so far.