The United States issued sanctions against Cuban state oil company Unión Cuba-Petróleo (CUPET), the Treasury Department website showed on Thursday.
The action freezes any US assets of the company and generally bars Americans from dealing with it.
"Today, I am designating Cuba's state-owned oil and gas company Union Cuba-Petroleo (CUPET), key assets of which were unlawfully expropriated from American owners years ago," US Secretary of State Marco Rubio said in a statement.
Washington has imposed sanctions on an array of Cuban entities and people, including the island nation's president, as it seeks to intensify pressure on Cuba's communist leaders.
The sanctions follow the United States' declaration of a national emergency this year that would impose tariffs on any country that supplies oil to the island, a move that has resulted in frequent power outages.
