President Trump said on Monday that he would crack down on countries that bought Venezuela’s oil by imposing tariffs on goods those nations sent into the United States, claiming that Venezuela has “purposefully and deceitfully” sent criminals and murderers into America.

In a post on Truth Social, the president said countries that purchased oil or gas from Venezuela would be forced to pay a tariff of 25 percent on any exports they sent to the United States, starting April 2.

This unconventional use of tariffs could further disrupt the global oil trade as buyers of Venezuelan oil and gas seek alternatives. The United States and China have been the top buyers of Venezuelan oil in recent months, according to Rystad Energy, a research and consulting firm. India and Spain also buy a small amount of crude from the South American country.

But in the case of China, Venezuela’s oil makes up such a small portion of the country’s imports that the threat of higher tariffs will probably cause China to look elsewhere for oil, said Jorge León, a Rystad Energy analyst.

American purchases of Venezuelan oil are poised to wind down after the Trump administration said it would revoke a license that allowed Chevron to produce oil there.

But as Mr. Trump threatened steeper tariffs on other countries, his administration on Monday gave Chevron, the second largest U.S. oil company, another two months to produce oil in Venezuela and sell it to the United States. The administration had earlier ordered Chevron to wind down its operations by April 3.

The U.S. and Venezuelan governments have been sparring over Mr. Trump’s plans to deport migrants from the United States. Venezuela announced on Saturday that it had reached an agreement with the Trump administration to resume accepting deportation flights of migrants who were in the United States illegally.

“Venezuela has been very hostile to the United States and the Freedoms which we espouse,” the president wrote. “Therefore, any Country that purchases Oil and/or Gas from Venezuela will be forced to pay a Tariff of 25% to the United States on any Trade they do with our Country.”

Mr. Trump is planning to impose new tariffs globally on April 2, when he will introduce what he is calling “reciprocal tariffs.” He has said the United States will raise the tariffs it charges on other countries to match their levies, while also taking into consideration other behaviors that affect trade, like taxes and currency manipulation. The president has taken to calling this “liberation day,” a label he repeated on Monday.

Mr. Trump called the new levies he threatened on buyers of Venezuelan oil “secondary tariffs.” They would be an unusual use of tariffs, and it’s not entirely clear how they would work. Some trade and sanctions experts said existing secondary sanctions associated with countries such as Russia and Iran already weren’t well enforced, and questioned whether the United States would have the capacity to pull off new tariff-based penalties.

“Given the limited enforcement of existing secondary sanctions, where we have a precedent, I’m not sure how realistic effective deployment of this strategy is,” said Daniel Tannebaum, a partner at Oliver Wyman who advises multinational companies on sanctions.

But the strategy could help the United States to avoid putting financial sanctions on foreign banks that could threaten financial stability. Using tariffs could help the United States to be seen as taking tough action without incurring those risks.

With typical secondary sanctions, individuals or companies cannot buy oil or other products under sanctions from a blacklisted country. Otherwise, businesses could be subjected to U.S. sanctions themselves, facing fines or being cut off from the U.S. financial system.

But Mr. Trump and his advisers have said they think such sanctions can threaten the pre-eminence of the dollar if they are overused, by encouraging other countries to find alternative currencies. They have talked about using tariffs instead.

In his confirmation hearing in January, Scott Bessent, the Treasury secretary, said tariffs, in addition to raising revenue and rerouting supply chains, could provide an alternative to traditional financial sanctions.

Mr. Trump “believes that we’ve probably gotten over our skis a bit on sanctions and that sanctions may be driving countries out of the use of the U.S. dollar.” Tariffs could be used instead, Mr. Bessent said.