US Treasury Secretary Steve Mnuchin has said he expects President Donald Trump to impose new sanctions on Iran.
The news comes as Mr Trump faces a Friday deadline to decide whether to waive other major sanctions on Iran lifted under the 2015 nuclear deal.
Earlier, European powers urged Mr Trump to uphold that agreement, saying it was vital for international security.
Mr Trump has criticised the deal, which saw sanctions lifted when Iran agreed to limit its nuclear fuel production.
Mr Mnuchin told reporters he was expecting new sanctions on Iran to be announced – which previous reports have suggested could be targeted measures against Iranian individuals and businesses.
“We continue to look at them. We’ve rolled them out and I think you can expect there will be more sanctions coming.”
The US president says he wants to amend the deal – or withdraw from it completely.
In October, he refused to recertify for Congress that Iran was complying with the deal, accusing it of “not living up to the spirit” of the agreement.
The BBC’s Gary O’Donoghue, in Washington, says that while the future of the major sanctions is an open question, the new measures could help the president fend off criticisms from his supporters that he’s not fulfilling a key campaign promise to “rip up” the nuclear deal with Iran.
Why does Europe back the deal?
The foreign ministers of Britain, France, Germany and the European Union met their Iranian counterpart Mohammad Javad Zarif in Brussels on Thursday to reaffirm their commitment to the accord, which was also backed by China and Russia.
At a news conference afterwards, representatives of the EU, the UK, France and Germany reiterated their support for the nuclear deal they helped negotiate.
“The deal is working; it is delivering on its main goal, which means keeping the Iranian nuclear programme in check and under close surveillance,” EU foreign policy chief Federica Mogherini said.
“The unity of the international community is essential to preserve a deal that is working, that is making the world safer and that is preventing a potential nuclear arms race in the region. And we expect all parties to continue to fully implement this agreement.”
UK Foreign Secretary Boris Johnson insisted the deal was preventing Iran from acquiring nuclear weapons, and challenged Washington to come up with a better alternative.
He described the deal, which is known formally as the Joint Comprehensive Plan of Action (JCPOA), as a “considerable diplomatic accomplishment”.