During a NATO summit in Ankara, which European leaders had hoped would put a lid on rifts within the military alliance, Trump instead reignited the dispute with Spain.
He also irked another NATO ally Denmark by reiterating that his country should control Greenland.
It was the second time Trump has instructed Treasury Secretary Scott Bessent to halt commerce with Spain over its refusal to commit to NATO's new defence spending target of five per cent of GDP.
However, after his first such promise in March, trade between the two countries continued normally.
"Spain doesn't agree to anything, and you shouldn't carry them," Trump told NATO Secretary-General Mark Rutte, who later tried to soothe the tension by saying that Spain "made a huge step last year" raising its spending to two per cent, although he added that "there are still issues we have to solve".
"I don't want to do any trade with them, all right?" Trump said, turning to Bessent, who replied: "Yes, sir."
Trump then added, "Take it immediately. Don't even talk to them. They're hopeless. They're bad people ... They make so much money with us, and we're going to see that they make a lot less."
The office of Spanish Prime Minister Pedro Sanchez, who leads a minority leftist government, said it was treating Trump's statements as "business as usual" and did not intend to change the "excellent" relations it enjoyed with Washington.
It pointed out that Spain had a trade deficit with the US and that economic ties were forged by private companies rather than governments, adding that as part of the customs and trade union, individual EU members could not be singled out.
Trump has repeatedly expressed frustration with Spain after Sanchez refused to let the US use its airspace or bases on its territory for the Iran war.
Spain is the world's largest olive oil exporter and also sells auto parts, steel, and chemicals to the United States, although analysts consider it to be less vulnerable to Trump's threats of economic punishment than other European economies.
