Iran has rejected as "excessive and illogical" a demand by US President Barack Obama that it freeze sensitive nuclear activity for at least 10 years.
Iranian Foreign Minister Javad Zarif was quoted saying Mr Obama spoke in "unacceptable and threatening" terms.
Mr Zarif said talks on Iran's nuclear programme, which are nearing a critical 31 March deadline, would continue.
Israeli Prime Minister Benjamin Netanyahu is expected to urge the US Congress on Tuesday to oppose a deal.
He was invited to speak at the US Capitol by Republican House Speaker John Boehner, angering Democrats.
Mr Netanyahu - who faces domestic elections in two weeks' time - will not meet Mr Obama during his visit to the US.
In his interview with Reuters news agency, the US president said disagreements over Iran would not be "permanently destructive" to the US-Israel relationship.
But Mr Netanyahu had been wrong on Iran before when he opposed an interim nuclear agreement struck last year, Mr Obama said.
Mr Obama also said Iran should agree to freeze sensitive nuclear activity if it wants to strike a deal with the US. However, he said, the odds were against talks with Iran ending in agreement.
In a response quoted by Iran's semi-official Fars news agency, Mr Zarif said his country would "not accept excessive and illogical demands".
He added that Mr Obama's comments were aimed at public opinion in the US, and intended as a counter to the "propaganda" of those who opposed the negotiations - including Israel's prime minister.
US Secretary of State John Kerry met Mr Zarif in Switzerland on Tuesday, as part of ongoing talks ahead of a 31 March deadline for a framework agreement. The aim is then to secure a final deal by 30 June.
In remarks to reporters after the meeting, Mr Zarif emphasised both sides were committed to reaching a deal.
"There is a seriousness that we need to move forward," he said. "We need the necessary political will to understand that the only way to move forward is through negotiations."
Analysis: Jeremy Bowen, BBC Middle East editor
Mr Netanyahu is due to be presented with a bust of Winston Churchill by the Republican speaker John Boehner, who controversially invited him to speak in Washington without discussing the matter with the White House.
The Israeli prime minister sees himself as Churchill's heir, warning against Iran as Churchill warned against the Nazis.
But he's also been accused of political calculation - helping out his Republican friends and making the speech part of his campaign in the Israeli general elections a fortnight from now.
The Obama administration is countering by pointing everything it does for Israel, from $20bn in military aid since President Obama was first elected to the use of the veto in the UN Security Council to protect Israel diplomatically.
The US, UK, France, Germany, Russia and China are seeking to reach agreement to curtail Iran's nuclear programme in exchange for sanctions relief.
They are trying to address concerns that Iran is seeking nuclear weapons technology, something Tehran denies.
The Israelis say any agreement that leaves Iran with the potential to use a peaceful civilian nuclear programme for military means, now or in the future, is unacceptable.
The leading Republican and Democrat on the House foreign relations committee have sent a letter to Mr Obama highlighting their concerns about a deal.
They said Congress must be convinced that any pathway Iran might have to developing a nuclear weapon is shut off before Congress considers easing sanctions.
Nuclear Iran: What world powers want - and what they fear
- World powers imposed sanctions on Iran because they felt it was not being honest about its nuclear programme and was seeking the ability to build a nuclear bomb.
- Tehran denied this. Talks between Iran and six world powers known as the P5+1 have tried to allay the suspicions in exchange for easing the sanctions
- Specifically, the world powers want to curtail Iran's ability to enrich uranium, which can be used to make reactor fuel but also nuclear weapons
- Disagreement centres on how to limit Iran's development and use of centrifuges that enrich uranium
- Faster enrichment would cut the time Iran would need to produce enough weapons-grade uranium for a weapon, were it to choose to do so. The US wants this "break-out window" to be at least a year long
- It is not known if Iran has a warhead or suitable delivery system