"As usual, not a level playing field".
The US dollar fell against major currencies on Mr Trump's threat to impose more import tariffs and his repetition of complaints about rising interest rates and the strength of the US dollar.
There is already pushback in the USA from businesses that will take a hit in an escalating trade war.
That would equal the amount of annual Chinese exports to the US for the year.
In a taped interview with the business channel CNBC, Trump said "I'm willing to go to 500", referring roughly to the $505.5 billion in goods imported past year from China.
Those comments, plus Trump's criticism of Federal Reserve interest rate hikes, caused the dollar to fall back against other currencies, however, including the pound which rebounded from 10-month lows versus the greenback.
Trump's comments will make life hard for both the Treasury and the Fed, said Tony Fratto, former White House deputy press secretary under George W. Bush and founder of Hamilton Place Strategies in Washington. "No president should interfere with the workings of the Fed", Fisher said.
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"We're down a tremendous amount", Trump said in an interview about trade imbalances with China on CNBC broadcast on Friday.
Powell added that "no one in the administration has said anything to me that really gives me concern on this front". But at the same time I'm letting them do what they feel is best, ' Trump said.
"I'm ready to go to $500 [billion]", Trump added.
The US dollar lost ground against rival currencies following the comments.
"I've been surprised that up until now, markets seem overly sanguine about the risks" of a trade war between the world's two biggest economies, said David Dollar, senior fellow at the Brookings Institution's China studies center and a former official at the World Bank and U.S. Treasury Department.
America's central bank has twice increased benchmark lending rates this year, following three raises last year. Its rate hikes are meant to prevent the economy from overheating and igniting high inflation.
'I'm not happy about it. "I want them to do well", he said.
During the 2016 campaign, Trump said she should be "ashamed of herself" for creating a "false stock market" with low rates.
The dollar index turned negative following the release of Trump's remarks, which were excerpted from a longer interview due to air Friday morning. He also called Jerome Powell, whom Trump nominated to lead the Fed, a "very good man".