Iran's President Mahmoud Ahmadinejad says US accusations Tehran is fomenting violence in Iraq are an attempt to hide Washington's own failures.
Mr Ahmadinejad said foreign forces should leave Iraq
Mr Ahmadinejad made the comments in a rare US television interview on Monday.
US officials in Iraq had said they had evidence that Iran was providing weapons to Shia militias who attacked the US military.
Mr Ahmadinejad said Iran "shied away from all conflict" and that no peace would come with foreign troops in Iraq.
In the interview with ABC Television in Tehran, Mr Ahmadinejad was questioned repeatedly about the US claims.
He said the accusations were "excuses to prolong the stay" of US forces.
"There should be no foreigners there in Iraq. And then you see that you have peace in Iraq," Mr Ahmadinejad said.
He said any claims of Iranian military supplies should have a "court to prove the case".
Mr Ahmadinejad said: "We have made it clear the lack of security in Iraq is to our disadvantage."
Earlier Iranian Foreign Ministry spokesman Mohammad Ali Hosseini had called the US allegations baseless propaganda.
He said Washington had a long history of fabricating evidence.
On Sunday, US officials said they had proof that Iran had provided sophisticated weapons which had been used to kill American soldiers in Iraq.
The US claims have not been independently verified.
The Bush administration denies it is planning to invade Iran but has indicated it is willing to use military force to deal with any Iranian interference inside Iraq.
Democratic Senator Chris Dodd said the Bush administration had tried to falsify evidence before, and it would be a mistake to create a premise for future military action.
Mr Ahmadinejad told ABC he thought the possibility of an attack "very low".
"We believe there are wise people in the US who will stop such illegal actions," he said.
"Anyone who wants to attack our country will be seriously punished."