Iranian President Mahmoud Ahmadinejad has said that a US report on Tehran's nuclear programme is a "great victory".
Mr Ahmadinejad vowed Iran would pursue its "peaceful programme"
He said in a televised speech that the report had been a "fatal blow" to those who had filled the world for several years with threats, stress and anxiety.
The US intelligence assessment released on Monday said that Iran had halted a nuclear weapons programme in 2003.
The head of the International Atomic Energy Agency, Mohamed ElBaradei, said Iran had been "somewhat vindicated".
Mr ElBaradei told reporters in the Brazilian capital, Brasilia, that the assessment had also been a "sigh of relief" for the IAEA because the conclusions were similar to its own.
"I see this report as a window of opportunity. It's a window of opportunity because it gives diplomacy a new chance," he added.
The US and its European allies on the UN Security Council have been pushing for tougher sanctions, but Russia and China have said the report raises questions about the need for new measures.
US President George W Bush said on Tuesday that Iran remained a threat and his view that a nuclear Iran would be a danger "hasn't changed".
Mr Ahmadinejad made his televised speech in front of thousands of people during a visit to Ilam province in western Iran.
"This report... is announcing a victory for the Iranian nation in the nuclear issue against all international powers," he said
"You saw the report of the US intelligence. They said clearly that the Iranian people were on the just path."
Calling the report a "final blow", he warned: "If you want to start up a new game, the Iranian people will resist and will not step back one inch.
"If you want to negotiate with us as an enemy, the Iranian people will resist and will conquer you. If it is on the basis of friendship and co-operation, the Iranian people will be a great friend."
The BBC's Jon Leyne in Tehran says President Ahmadinejad is relishing the moment particularly at a time when he had been facing growing criticism within the political elite.
The US National Intelligence Estimate (NIE) report had said with "high confidence" that it believed Iran had halted its nuclear weapons programme in 2003, but that it was continuing to enrich uranium.
The US has vowed to push for a third UN sanctions resolution.
The text of a draft resolution could be circulated by the end of the week, says the BBC's Laura Trevelyan at the UN.
However, Russian Foreign Minister Sergey Lavrov has said that there was no proof that Iran has ever run a nuclear weapons programme.
"Data that we have seen don't allow us to say with certainty that Iran has ever had a nuclear weapons programme," Mr Lavrov said.
And on Tuesday, China's ambassador to the UN, Wang Guangya, said "things have changed" and the push for new sanctions would need to be questioned.
China had agreed only reluctantly to earlier resolutions after Iran refused to heed a Security Council call to abandon uranium enrichment.
China and Russia are permanent members of the council and can block any resolution.
Some Western powers believed the process was being used as part of a weapons programme although Tehran has always said its work is for peaceful energy purposes.
The NIE report also said Iran was keeping its options open on developing nuclear weapons. It said Tehran could have enough highly enriched uranium to build a bomb within three to eight years.
Mr Bush called the report a "warning signal".
"Iran was dangerous, Iran is dangerous and Iran will be dangerous if they have the knowledge necessary to make a nuclear weapon," he said.
"The best diplomacy, effective diplomacy, is one in which all options are on the table."