His remarks have broken a long-standing tradition of United States presidents not commenting on the Fed's policies to preserve the central bank's independence. "Now it is taking 15 days or longer".
On Thursday, the European Union said it was developing plans to hit back at the USA if it attempted to place import tariffs on cars, something Trump has repeatedly threatened to do.
On Wall Street, the Dow Jones Industrial Average rose 9.71 points, or 0.04 percent, to 25,074.21, the S&P 500 gained 0.39 points, or 0.01 percent, to 2,804.88 and the Nasdaq Composite added 9.01 points, or 0.12 percent, to 7,834.31.
A top Federal Reserve official, meanwhile, warned the trade war could hurt the USA economy. Once tariffs go into place, importers face the extra fee immediately.
Iris Pang, chief China economist of ING Bank, said China was resisting responding to Trump's rhetoric this time, partly because the U.S. leader may be only bluffing. -China trade war and the other conflicts President Trump has ignited.
Still, new tariffs could help Mr Trump's Republican party going into November's congressional elections.
"That isn't how trade negotiations work", Yerxa said.
Trump said he and Chinese President Xi Jinping maintain a good relationship despite the growing dispute over trade.
China will likely retaliate if additional tariffs are imposed, economists note, rather than simply knuckle under.
Philip Levy, a trade expert at the Chicago Council on Global Affairs and a former White House trade adviser, suggested that Chinese officials have been frustrated and confused by their previous failed efforts to reach an agreement.
Later in a pair of tweets, Trump attacked China and the European Union for keeping their currencies low to gain a trade advantage, while again blasting the Federal Reserve for raising interest rates.
Analysts said letting it weaken costs China little - for now - while easing the impact of the tariffs.
Yet President Trump soon intensified his tariff threats anyway. "They've received conflicting messages depending on who they speak with".
Treasury Secretary Steven Mnuchin said Friday that the U.S.is closely monitoring whether China has manipulated its FX rate, according to Reuters. Yet any such agreement would require extensive talks over how it would be implemented and verified.
"I'm doing this to do the right thing for our country", Trump said in a CNBC interview aired Friday.
"Automobiles - that's the 800-pound gorilla", Brookings' Dollar said.
In a television interview on Thursday, US network CNBC quoted Mr Trump saying a strong dollar "puts us at a disadvantage" and adding that the Chinese yuan "has been dropping like a rock".
Trump has always been a fan of tough action on trade. He has been denouncing other countries' trade practices and urging retaliation for decades, dating to the 1980s, when Japan was regarded as America's main global economic threat.
"The central bank wants to use the currency movements to achieve internal and external economic balance".
When asked during Friday's interview, "Will you ever get to 500, though?"