Israeli Prime Minister Benjamin Netanyahu has used his speech to the United Nations General Assembly to warn against working with the Iranian government.
He insisted Tehran still wants to destroy Israel, despite comments by new president Hassan Rouhani.
"Rouhani doesn't sound like (former Iran president Mahmoud) Ahmadinejad but when it comes to Iran's nuclear weapons programme, the only difference between them is this: Ahmadinejad was a wolf in wolf's clothing. Rouhani is a wolf in sheep's clothing," Mr Netanyahu said.
Mr Rouhani was trying to pull the wool over the international community's eyes, he said.
Iran told the general assembly it had no intention of developing nuclear weapons and described Mr Netanyahu's speech as highly inflammatory.