Iran is to partially suspend co-operation with the United Nations nuclear watchdog.
Tehran's scaling back of co-operation with the International Atomic Energy Agency (IAEA) is in apparent retaliation for the sanctions unanimously approved by the UN security council over Tehran's refusal to stop enriching uranium, a process that can be used in the production of nuclear weapons.
A government spokesman said the suspension of some areas of co-operation with the IAEA would "continue until Iran's nuclear case is referred back to the IAEA from the UN Security Council".
Iranian state television quoted President Mahmoud Ahmadinejad as saying the additional UN Security Council sanctions imposed on Saturday "stem from the hostility by some powers" against Iran.
"It is not a new issue for the Iranian nation. Enemies of the Iranian nation have made a mistake this time too," Mr Ahmadinejad said, adding the new sanctions "will not halt Iran's peaceful nuclear programme even for a second".
The West strongly suspects Iran's nuclear activities are aimed at producing weapons; Tehran says they are exclusively for the production of energy.
The UN sanctions are meant to send Tehran a strong message that its defiance will leave it increasingly isolated and open to even tougher penalties.