Donald Trump says Chinese-made smartphones and other electronics will not be exempt from tariffs - adding they are simply moving into a different levy "bucket".
European stock markets bounced up on Monday morning after Friday's official announcement that some of these products would escape levies of up to 145%.
China has called on Donald Trump to "completely cancel" his tariffs regime, and "return to the right path of mutual respect".
However US officials said on Sunday that products would be subject to a "semiconductor tariff" instead, with Trump expected to reveal more details later.
US Commerce Secretary Howard Lutnick said the new levy would be in addition to a host of global tariffs the US imposed earlier this month, then paused for 90 days.
"We need our medicines and we need semiconductors and our electronics to be built in America," he added.
On Saturday, a US customs notice revealed smartphones, computers and some other electronic devices would be excluded from the 125% tariff on goods entering the country from China.
But Trump chimed in on social media, saying there was no exemption for these products and called such reports about this notice false. Instead, he said that "they are just moving to a different Tariff 'bucket'".
Trump added: "We are taking a look at Semiconductors and the WHOLE ELECTRONICS SUPPLY CHAIN in the upcoming National Security Tariff Investigations."
He said he would provide an update on Monday about semiconductor duties.
Everyday devices such as smartphones and laptops rely on semiconductors, which are small and powerful pieces of tech that form the basic building blocks of modern computation.
On Monday, Sony announced that it was increasing the price of its flagship games console, the PlayStation 5, by about 10% in Europe, Australia and New Zealand, citing a "challenging economic environment", inflation and fluctuating exchange rates. It did not announce price rises in the United States.
The Chinese commerce ministry had called Trump's exemptions a "small step" by the US, and said that Beijing was "evaluating the impact" of the move.
But the suggestion by Trump administration officials of plans for future levies may dampen hopes of a thaw in the two rivals' protectionist posture.
US Trade Representative Jamieson Greer was asked on Sunday whether there were any plans for Trump to speak with his Chinese counterpart, Xi Jinping.
"Right now we don't have any plans on that," he said during an appearance on CBS's Face the Nation.
Trump imposed a tariff amounting to 54% on imports of products from China at the beginning of April, before escalating to the current 145% rate.
In its own tit-for-tat tariffs, China imposed levies of 34% on US goods, before increasing it to 84% and then 125%, which took effect on Saturday.
In announcing its latest tariffs, China's commerce ministry said last week that it would "fight to the end" if the US "insists on provoking a tariff war or trade war".
Late on Saturday, while travelling to Miami, Florida, Trump said he would give more details of the exemptions at the start of next week.
The White House has argued that it is using tariffs as a negotiating tactic to extract more favourable trade terms from other countries.
Trump has said his policy will redress unfairness in the global trading system, as well as bring jobs and factories back to the US.
However, his interventions have seen massive fluctuations in the stock market and raised fears of a decrease in global trade that could have a knock-on effect on jobs and individual economies.
