WASHINGTON—The U.S. threatened to slap sanctions on countries that don’t cut oil imports from Iran to “zero” by Nov. 4, part of the Trump administration’s push to further isolate Tehran both politically and economically, a senior U.S. State Department official said.

Buyers of Iranian crude had expected the U.S. would allow them time to reduce their oil imports over a much longer period, by issuing sanctions waivers for nations that made significant efforts to cut their purchases. That expectation was partly based on previous comments from top Trump officials, as well as the Obama administration’s earlier effort to wean the world off Iranian oil over several years.

But the senior State Department official said on Tuesday that President Donald Trump’s administration doesn’t plan to issue any waivers and would instead be asking other Middle Eastern crude exporters over the coming days to ensure oil supply to global markets.

The tactic is likely to further escalate geopolitical tensions between the U.S. and other nations as the Trump administration pits itself against its allies and other major economies over its nearly unilateral policy toward Iran and a host of challenges on trade.

Oil prices immediately jumped on the news, with West Texas Intermediate crude for August delivery ending 3.6% higher at $70.53 a barrel on the New York Mercantile Exchange. That marked the highest level since May, when the White House said it would pull out of the 2015 Iran nuclear accord—which the U.S. and other major countries reached with Tehran to curb its nuclear development—and would reimpose crushing sanctions on one of the world’s largest oil suppliers.