Iranian President Mahmoud Ahmadinejad has warned the European Union against imposing sanctions, saying his country would cause it to "regret" the move.
Mr Ahmadinejad said that anyone who adopted hostile measures "should know that Iran will react swiftly".
EU foreign ministers are expected on Monday to formally approve restrictions on Iran's energy sector, to impede the development of its nuclear programme.
The decision comes a month after the US strengthened its own sanctions on Iran.
The US and its allies accuse Tehran of seeking to develop nuclear weapons. Iran insists its nuclear programme is solely for peaceful purposes.
BBC News
