The Trump administration is to reinstate all US sanctions on Iran that were removed as part of the 2015 nuclear deal.
However, eight unnamed countries will not be penalised by the US for continuing to import Iranian oil.
President Donald Trump withdrew from the deal in May, describing it as "defective at its core".
The agreement saw Iran limit its controversial nuclear activities in exchange for sanctions relief.
Barack Obama, the US president at the time, had argued the deal would prevent Iran from developing nuclear arms.
The UK, France, Germany, Russia and China were also parties to the 2015 accord and have stuck to it, saying they will set up a new payment system to maintain business with Iran and bypass US sanctions.
Trump argues that the terms of the deal are unacceptable and it has not stopped Iran developing a ballistic missile programme and intervening in neighbouring countries, including Syria and Yemen.
Iran has accused Trump of waging "psychological warfare".
