US President Donald Trump has said he is imposing hard-hitting new sanctions on Iran, including on the office of the country's Supreme Leader Ali Khamenei.
Mr Trump said the additional sanctions were in response to the shooting down of a US drone and "many other things".
He added that they would "continue to increase pressure on Tehran", saying "never can Iran have a nuclear weapon".
Tensions between the two countries have been escalating in recent weeks.
Last week, Iran shot down an unmanned US drone in the Gulf.
It had earlier announced it would breach the limit on its stockpile of enriched uranium set under a 2015 nuclear deal with world powers.
The deal had seen relevant sanctions were lifted, but the US pulled out last year and reinstated sanctions.
They have pushed the value of its currency to record lows and driving away foreign investors.
