Iran's President Mahmoud Ahmadinejad has rejected international calls for Tehran to suspend uranium enrichment, a day before a UN deadline runs out.
Mahmoud Ahmadinejad says the UN cannot set pre-conditions for talks
He said Iran would only do so if states seeking the suspension stopped producing nuclear fuel themselves.
Mr Ahmadinejad said he wanted talks on his nation's nuclear programme, but only if no pre-conditions were imposed.
Iranian nuclear negotiator Ali Larijani said after talks at the UN nuclear agency no solution would come by force.
Mr Larijani said at the talks at the International Atomic Energy Agency (IAEA) in Vienna: "Anybody interested in non-conventional or illogical, irrational [moves] would definitely receive an appropriate response."
But he said Iran was looking "for ways and means to start negotiations".
Speaking on the issue on a visit to Turkey, Iran's Foreign Minister Manouchehr Mottaki echoed the view.
"The way to solve problems through diplomacy is dialogue," he said.
Details have emerged of US contingency plans for air strikes on Iran.
The US insists it is not planning to attack, and is trying to use diplomacy to persuade Tehran to stop uranium enrichment.
Tehran insists its programme is for civil use only, but Western countries suspect Iran is trying to build nuclear weapons.
Iran will face sanctions if it fails to observe Wednesday's UN Security Council deadline on enrichment.
IAEA head Mohamed ElBaradei has warned in a UK media interview of the speed at which Iran's nuclear work is advancing.
He is due to report to the UN Security Council this week on whether Iran has met UN demands that it halt uranium enrichment by 21 February.
If it does not, and if the International Atomic Energy Agency confirms this, the council's resolution says that further economic sanctions will be considered.
Iran resumed uranium enrichment work last year
In a speech to crowds in northern Iran, broadcast on state television, Mr Ahmadinejad called on Western nations to stop their own nuclear enrichment programmes if they wanted Iran to do the same.
He said: "They tell us 'come and negotiate on Iran's nuclear issue but the condition is to stop your activities.
"We have said that we want negotiations and talks, but negotiations under just conditions.'"
The US dismissed the call to close down Western production facilities.
"Do you believe that's a serious offer?" said White House spokesman Tony Snow.
Last year Iran resumed uranium enrichment - a process that can make fuel for power stations or, if greatly enriched, material for a nuclear bomb.
Mr Larijani said his country was willing to give reassurances that no nuclear material would be diverted to a weapons programme but he remained defiant on uranium enrichment.
Mr ElBaradei told the Financial Times newspaper Iran could be only six months away from being able to enrich uranium on an industrial scale.
But he said "there's a big difference between acquiring the knowledge for enrichment and developing a bomb".
Mr ElBaradei also suggested the use of military force against Iran "would be catastrophic" and urged the Security Council to look at incentives as well as sanctions to bring Tehran back to the table.
The US has been pushing hard for the international community to take tough action should Iran not meet the council's demands.