"We have a tanker out there. We don't mind having somebody get a boatload because they need … they have to survive," Trump told reporters as he flew back to Washington from Florida on Sunday.
Trump was asked if a New York Times report that the tanker would be allowed to reach Cuba was true.
"I told them, if a country wants to send some oil into Cuba right now, I have no problem whether it's Russia or not," he said.
Tracking data shows the oil tanker carrying approximately 730,000 barrels of oil, was just off the eastern tip of the island on Sunday night and slated to arrive in the city of Matanzas by Tuesday.
Journalists working for Cuban state media also reported the on the boat's expected arrival, though Cuban officials did not immediately respond to a request for comment.
The vessel, Anatoly Kolodkin, is sanctioned by the United States, the European Union and the United Kingdom following the war in Ukraine.
Trump, whose government has come at its Caribbean adversary more aggressively than any US government in recent history, has effectively cut Cuba off from key oil shipments in an effort to force regime change.
The blockade has had devastating effects on the civilians Trump and Secretary of State Marco Rubio say they want to help, leaving many desperate.
Experts say the anticipated shipment could produce about 180,000 barrels of diesel - enough to feed Cuba's daily demand for nine or 10 days.
Island-wide blackouts have roiled Cubans already grappling with years of crisis, and lack of gasoline and basic resources has crippled hospital and slashed public transport.
Cuba has long been at the heart of geopolitical tug-of-war between the US and Russia, dating back decades. Trump on Sunday dismissed the idea that allowing the boat to reach Cuba would help Russian President Vladimir Putin.
"It doesn't help him. He loses one boatload of oil, that's all it is. If he wants to do that, and if other countries want to do it, it doesn't bother me much," Trump said.
"It's not going to have an impact. Cuba's finished. They have a bad regime. They have very bad and corrupt leadership and whether or not they get a boat of oil, it's not going to matter."
"I'd prefer letting it in, whether it's Russia or anybody else because the people need heat and cooling and all of the other things."
