Iranian President Mahmoud Ahmadinejad has said Tehran will not abandon its right to nuclear technology under Western pressure, local media say.
The UN has agreed new plans to try to halt Iran's nuclear work
His statement comes a day after six world powers agreed proposals in Vienna to persuade Iran to halt its research.
But US Secretary of State Condoleezza Rice said she still hoped to meet ministers from Iran if it suspended its nuclear programme and agreed to talks.
Ex-President Jimmy Carter said the US should enter talks without conditions.
"To say 'We will not meet with you unless you agree ahead of time to comply with all of our demands' might be an impediment that is too great politically speaking for the Iranian government to overcome," he told the BBC.
However, the Bush administration has made clear it will only talk to Iran if they suspend their uranium enrichment while Tehran has dismissed the offer of incentives and talks, saying it is not prepared to give up its nuclear programme.
That has left the likelihood of the two sides talking in serious doubt, the BBC's Jonathan Beale reports from Washington.
US Director of National Intelligence John Negroponte said Iran could have a bomb within 10 years.
Iran resumed enrichment of uranium this year but remains a signatory to the nuclear Non-Proliferation Treaty and maintains that its activities are aimed only at energy production.
Mr Ahmadinejad said Iran had co-operated and would continue to co-operate with UN nuclear watchdog the International Atomic Energy Agency.
He said that at issue was the right to advanced technology, not nuclear weapons.
"The efforts of some Western countries to deprive us will not bear any fruit," he said.
He made no direct reference to Thursday's proposal, which contains both incentives and penalties depending on whether Iran decides to give up or continue sensitive nuclear activity.
Although no details have been made public of the Vienna accord, sources say it could include giving Iran a nuclear reactor and an assured supply of enriched uranium.
European officials are expected to acquaint Tehran with the proposal in the next few days.
'Ministers could meet'
Ms Rice said she hoped for an Iranian reply within weeks, but warned Tehran could face robust measures if it turned down the offer.
Mr Negroponte said Iran could have a nuclear bomb by 2015
She said it was possible she would meet Iranian ministers, in what would be the highest level of contact between the two countries since 1979.
"If Iran is prepared to verifiably suspend its programme and enter into negotiations, then we'll determine the level [of representation] but I wouldn't be at all surprised if the ministers meet at some point," she said, quoted by Reuters news agency.
Speaking in Moscow, President Putin of Russia stressed it was too early to talk of sanctions, saying there was a need to have a deep conversation with the Iranian leadership.
But the BBC's Jonathan Marcus says it is as hard to determine who really is in control in Tehran as it is to decide what the government's nuclear intentions are.
Earlier on Friday, Mr Negroponte told BBC Radio's Today programme Tehran could have a nuclear bomb ready between 2010 and 2015.
He also accused Iran of being the world's top state sponsor of terrorism.