The court ruled six to three on Friday that Trump does not have the authority to impose tariffs under a 1977 law he has relied on to impose sudden levies on individual countries, upending global trade.

Trump reacted furiously, announcing first a new 10 percent global duty on imports under a different legal authority, before raising it to 15 percent on Saturday.

China's commerce ministry said on Monday it was conducting a "comprehensive assessment" of the ruling's impact, and called on Washington to lift the tariffs.

"China urges the United States to cancel its unilateral tariff measures on its trading partners," the ministry said in a statement. "There are no winners in a trade war and that protectionism leads nowhere."

The new 15 percent global duties are due to kick in on Tuesday, and are expected to last 150 days with exemptions for some products.

The Chinese foreign ministry also noted that it was paying "close attention" to potential moves by the United States to maintain increased tariffs.

"The United States is currently planning alternative measures such as trade investigations in order to maintain increased tariffs on trading partners. China will continue to pay close attention to this and resolutely safeguard China's interests," it said.

The Supreme Court ruling was a stunning rebuke to Trump from a judicial body that has largely sided with him since his return to office.

It marked a major political setback in striking down his signature economic policy that has roiled the global trade order.

Several countries have said they are studying the Supreme Court ruling and Trump's subsequent tariff announcements.

US Trade Representative Jamieson Greer told US media on Sunday that the country's trade deals with China, the European Union and other partners will remain in force despite the ruling.