The US is aiming “to turn the temperature down” in the Middle East, the country’s ambassador to the UN has said, as fears of an Iranian retaliatory attack on Israel loom.

On Tuesday, Linda Thomas-Greenfield told the UN Security Council in New York the US wanted to “deter and defend against any future attack and avoid regional conflict”.

There are fears Iran could retaliate against Israel following July’s assassination of Hamas leader Ismail Haniyeh in Tehran – something Israel has not said it was behind.

US President Joe Biden suggested reaching a ceasefire deal between Israel and Hamas in Gaza could help deter Iran from launching an attack on Israel.

“That’s my expectation but we’ll see,” he said when asked by a reporter on Tuesday.

“We’ll see what Iran does and we’ll see what happens if there’s any attack, but I’m not giving up,” he said, while exiting his plane during a visit to New Orleans, Louisiana.

A new round of ceasefire talks is scheduled to take place in either Doha or Cairo on Thursday.

But a Hamas official in Lebanon, Ahmad Abdul Hadi, has said Hamas will not take part in the talks, according to reports by the New York Times and Sky News.

US Secretary of State Antony Blinken postponed plans to travel to the Middle East on Tuesday to participate in negotiations on a Gaza ceasefire deal.

International mediators from the US, Egypt and Qatar have been pushing for an agreement that would see Israeli hostages released to their families in exchange for Palestinian prisoners in Israeli jails.

Meanwhile, Washington has also approved new arms sales worth $20bn (£15.5bn) to Israel.

The state department said Israel would buy 50 F-15 fighter jets, as well as 33,000 tank cartridges, up to 50,000 mortar cartridges and new military cargo vehicles. The aircraft will begin to be delivered in 2029.

At the Security Council meeting in New York, Ms Thomas-Greenfield called for a ceasefire deal to be finalised.

“A broader regional conflict is not inevitable,” she said.

“The United States’ overall goal remains to turn the temperature down in the region, deter and defend against any future attacks, and avoid regional conflict,” she added.

“That starts with finalising a deal for an immediate ceasefire with hostage release in Gaza. We need to get this over the finish line.”

But Palestinian ambassador to the UN, Riyad Mansour, accused the Security Council of not doing enough to stop Israel’s military operation in Gaza.

“Wake up. Stop finding excuses. Stop imagining that you can reason with the Israeli government so it stops killing civilians by the thousands, imposing famine, torturing prisoners, colonising and annexing our land, all while you appeal to them, call on them, demand them to stop,” Mr Mansour said.

Israeli ambassador Gilad Erdan said the Israeli military took every possible measure to minimise collateral damage and accused Hamas of using civilians as human shields.

He also criticised the Security Council for not condemning the actions of Iran.

“As we speak here now, millions of Israelis are preparing for a direct Iranian attack, just as they did in April. Iran’s aggression threatens the entire region with war.”

Israel launched a military campaign in Gaza to destroy Hamas in response to an unprecedented attack on southern Israel on 7 October, during which about 1,200 people were killed and 251 were taken hostage.

More than 39,920 people have been killed in Gaza since then, according to the territory’s Hamas-run health ministry.

Hundreds of people have also been killed in the almost daily exchanges of fire between Hezbollah and the Israeli military across the Israel-Lebanon border since the day after the start of the conflict.

Amid a flurry of international diplomacy to de-escalate tensions, Iran on Monday dismissed calls from the UK and other Western countries to refrain from retaliation against Israel for the killing of Haniyeh.

Israel, which did not say it was involved in Haniyeh’s assassination, has meanwhile put its military on its highest alert level.

The US has warned that it is preparing for “a significant set of attacks” by Iran or its proxies as soon as this week, and has built up its military presence in the Middle East to help defend Israel.