President Donald Trump says he will fully enforce the sanctions being reimposed on Iran as a result of the US withdrawal from a 2015 nuclear deal.
Measures targeting Iran’s automotive sector as well as its trade in gold and other key metals will take effect from 00:01 EDT (04:01 GMT) on Tuesday.
Mr Trump believes the economic pressure will force Iran to agree to a new deal and end its “malign” activities.
Iran’s President Hassan Rouhani said the act was “psychological warfare”.
Responding on Iranian state television, Mr Rouhani rejected the idea of last-minute talks. “We are always in favour of diplomacy and talks… but talks need honesty,” he said.
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Mr Trump warned that individuals or entities who breach the sanctions risk “severe consequences”.
The UK, France and Germany – which were also parties to the 2015 accord along with Russia and China – have expressed “deep regret” at the US move.
