At the same time, Beijing warned President Trump not to split the international coalition over North Korea by provoking a trade war between China and the United States.
Trump signed an executive memorandum Monday afternoon instructing his top trade negotiator to launch an investigation into Chinese intellectual property violations, a move that could eventually result in severe trade penalties.
In China, these proposed measures were seen both as an attempt to pressure Beijing to act more strongly against North Korea and as an effort to shift the blame for the world's failure to rein in Pyongyang's nuclear and missile programs onto China alone.
"It is obviously improper to use one thing as a tool to impose pressure on another thing," Foreign Ministry spokeswoman Hua Chunying said Monday at a routine news conference.
With the commercial relationship between the two countries becoming more intertwined by the day, she said, a trade war is not a good idea. "There will be no winner," she said. "It will be lose-lose."
In an editorial, the state-owned China Daily newspaper said Trump was asking too much of China regarding North Korea, also known as the Democratic People's Republic of Korea, or DPRK.
Trump's "transactional approach to foreign affairs" is unhelpful, it said, while "politicizing trade will only exacerbate [the United States'] economic woes, and poison the overall China-U.S. relationship."
That won't bring results when it comes to North Korea, either, the editorial argued.
"By trying to incriminate Beijing as an accomplice in the DPRK's nuclear adventure and blame it for a failure that is essentially a failure of all stakeholders, Trump risks making the serious mistake of splitting up the international coalition that is the means to resolve the issue peacefully," it said.
"Hopefully Trump will find another path. Things will become even more difficult if Beijing and Washington are pitted against each other."
China accounts for roughly 90 percent of North Korean trade but moved in February to suspend North Korea's coal imports until the end of the year. Coal normally accounts for about half of North Korea's exports, but despite the coal ban, overall trade between the two countries has remained healthy.
Last month, China announced that imports from North Korea fell to $880 million in the six months that ended in June, down 13 percent from a year earlier. Notably, China's coal imports from North Korea dropped precipitously, with only 2.7 million tons being shipped in the first half of 2017, down 75 percent from 2016.
But iron ore imports grew sharply, reaching 1.34 million tons, worth an estimated $68 million, a 60 percent jump in the first half of the year.
A 29 percent spike in Chinese exports to North Korea — North Korea bought $1.67 billion worth of Chinese products in the first six months of the year — also helped push total trade between the two countries up 10 percent between January and June, compared with the same period last year.
The latest move to stem imports of iron, iron ore, lead and lead ore, as well as seafood products, will put significantly more pressure on Pyongyang. But it is unlikely to be enough to persuade North Korea to abandon its nuclear program, which it sees as essential to its own survival, experts say.
China is very reluctant to do anything that might destabilize the regime, which is a long-standing ally. It blames American hostility toward Pyongyang for forcing the regime to develop its nuclear program, and is urging dialogue to reduce tensions.
The move against China over trade was also seen here as an attempt to distract attention from Trump's domestic problems.
"Bashing China cannot solve U.S. economic problems, experts say," the state-run Xinhua news agency proclaimed.
The nationalist Global Times newspaper said a trade war with China could "boomerang" on Trump, because U.S. society and opinion could not withstand the losses that would result.
"If a China-US trade war starts, many of those who now support a hardline stance toward China would turn against the Trump administration," it wrote in an editorial.
It even tried to link developments to violence and "racial hatred" that broke out in Charlottesville, Va., over the weekend.
"The source of global instability may not be North Korea's nuclear ambitions nor Europe's refugee crisis, but the chaos in the US," it wrote in a separate opinion piece. "The public is also concerned that Trump is using international disputes to divert public attention away from the domestic turmoil."
Shirley Feng, Yang Liu and Luna Lin contributed to this report.