He said they've had a "big impact" in damaging China's economy, claiming Washington's trade deficit with Beijing has gone down substantially.
Mr Trump lashed out as as senior White House figures accused China of trying to destabilise United States democracy and presenting the most serious threat to its security.
"We expect the dynamic to change once we get a bit deeper into this, but for now China is trying to outrun the next round of tariffs", he said.
The increase, the result of both increasing exports from China to the USA - up 14.5 percent from the same month a year ago - and a decline in the goods that China is buying from the U.S.
China has responded by imposing counter tariffs, which the Trump administration alleges show political interference by targeting products from key states in next month's congressional elections.
Relations between the world's two largest economies have soured sharply this year, with US President Donald Trump vowing on Thursday to inflict economic pain on China if it does not blink.
"We were led badly when it came to trade", Trump told "Fox & Friends".
"The fundamentals of the USA economy continue to be extremely strong, I think that's why the stock market has performed as well as it has".
The Wall Street Journal and the Washington Post have cited officials as saying Trump has chose to proceed with a meeting with Xi.
But as USA interest rates have risen, the U.S. dollar has strengthened further, which makes American exports more expensive. "Markets tend to go too far in both directions and they have natural corrections".
Mnuchin met on Thursday with Yi Gang, head of China's central bank.
Mnuchin would not say what the report would reveal, but in the past Treasury has placed China on a watch-list but said it did not meet the requirements to be labeled a currency manipulator.
"I am concerned about the weakness in the currency".
The Treasury Department's congressionally mandated twice-a-year report assessing whether trade partners are manipulating their currencies is on track for release next week, the people said.
He said that in the discussions he had with the Chinese, they had made clear that they didn't see a further weakening of the Chinese yuan as being in their interests.
China's trade surplus with the United States surged to a record high of $34.13 billion in September, compared with $31.05 billion in August, Chinese customs data showed on Friday.
Concerns have been raised that China, the largest foreign holder of U.S. Treasurys, might start dumping its holdings as a way to pressure the United States in the trade dispute.
The currency has slid more than 9 percent against the dollar in the last six months, raising speculation that China has been deliberately weakening its currency as tensions with the USA escalate.
"That would be very costly for them to do", Mnuchin said.