Iran will hold the US responsible for any Israeli attack against the country, Ali Larijani, the speaker of Iran's parliament, has said.
His remarks came after Joe Biden, the US vice-president, said that Washington would not dictate the way Israel deals with Tehran's nuclear ambitions.
"We will consider the Americans responsible in any adventure launched by the Zionist entity," Larijani said in Doha, the capital of Qatar, on Monday during an official visit.
"No politician or person in the world can imagine that the Zionist entity can lead an operation without getting the green light from the United States."
Larijani said the Islamic republic's response to an attack would be "decisive and painful".
Biden said in an interview on Sunday that the US would not stand in the way of Israel in its dealings with Iran's nuclear ambitions.
"Israel can determine for itself - it's a sovereign nation - what's in their interest and what they decide to do relative to Iran and anyone else," he told ABC television.
"Whether we agree or not. They're entitled to do that ... We cannot dictate to another sovereign nation what they can and cannot do when they make a determination, if they make a determination, that they're existentially threatened."
Larijani said Biden's comments was "political manoeuvre. We have heard a lot of these words in the past".
"Biden, by saying that they (the United States) can't prevent such an operation, has taken the wrong route and revealed his card".
Asked about US calls for dialogue, Larijani said: "We want to work seriously. ... But on one side they tell us 'we want to resolve the problems and negotiate', on another we hear what Mr Biden says."
No 'green light'
Following the controversy triggered by Biden's interview, the US administration denied that it was giving Israel any green light to attack Iran or that it was reconsidering plans to engage diplomatically with Tehran.
"I certainly would not want to give a green light to any kind of military action," Ian Kelly, the US state department spokesman, said late on Monday.
But he echoed Biden's point that Washington considered Israel a "sovereign country" with a right to make its own military decisions.
"We're not going to dictate its actions," Kelly said.
"We're also committed to Israel's security. And we share Israel's deep concerns about Iran's nuclear programme."
Kelly brushed aside the idea that Biden was signalling a move by the Obama administration to drop its policy of diplomatic engagement with Iran, saying: "I wouldn't read into it any more than what you see."