The US has imposed sanctions on Venezuela’s state-owned oil firm PDVSA and urged the country’s military to accept a peaceful transfer of power.
National Security Adviser John Bolton said President Nicolás Maduro and his allies could “no longer loot the assets of the Venezuelan people”.
Efforts by the opposition to unseat Mr Maduro have increased in recent days.
The US and more than 20 countries have recognised opposition leader Juan Guaidó as interim president.
Treasury Secretary Steven Mnuchin said the proceeds of the purchase of Venezuelan oil would now be withheld from Mr Maduro’s government, but the company could avoid sanctions by recognising Mr Guaidó.
Venezuela is heavily reliant on the US for its oil revenue – sending 41% of its oil exports there – while it remains in the top four crude oil suppliers to the US.
Mr Maduro later announced he had told PDVSA to launch “political and legal action, in US and international courts” to protect its US subsidiary Citgo.