"It's not going to continue like that", Trump said from his golf club in Bedminster, N.J.
Trump has suggested he would go easier on China if it were more forceful in getting North Korea to rein in its nuclear weapons program.
Lighthizer will recommend whether an official investigation into trade practices is warranted.
United States President Donald Trump will sign an executive memorandum on Monday authorizing the US trade representative to determine whether to investigate China's intellectual property and trade or not.
Gordon Sun (孫明德), director of the Economic Forecasting Center under the Taiwan Institute of Economic Research, warned that if the US eventually imposes trade sanctions against China, "Taiwan should not take pleasure in (China's) misfortune". Trump has responded in bellicose terms over the progress of North Korea's nuclear missile program and threats to launch an attack on the USA territory of Guam, where the US has a military installation.
The administration official who confirmed that Trump would sign the order contended it was unrelated to the showdown with North Korea.
But as the North Korea crisis began to dominate headlines earlier this week, Trump fueled the impression that how hard he pressures Beijing on trade depends on its cooperation on the North Korea question. "They know how I feel", Trump told reporters on Thursday.
The United States has previously complained at the WTO about Chinese trade policies, including its "Made in China 2025" initiative, which seeks to have Chinese-made materials account for 70 percent of manufacturing inputs within the next eight years. That effort passed by a 15-0 vote.
The president's trade action will be a long way from any punitive move against China, despite his and his advisors' open talk of Chinese "theft" and "stealing" of US companies' intellectual property, which broadly includes technological innovations, film and other artistic products, industrial designs and military secrets.
But, the official added: "I don't think we're headed toward a period of greater conflict. In the end, consumers and businesses in both countries will suffer", he said.
At the same time, it could alienate China's leadership, which is urging the Trump administration to limit its confrontational language as it faces off against the regime in Pyongyang. "The current trajectory is unsustainable".
The latest step follows the opening by the Trump administration of several other investigations into Chinese commercial practices, notably in the steel sector.
A possible move by the United States to launch an investigation into China's unfair trade practices based on Section 301 of the Trade Act has Taiwan anxious because many of its products sold to the US are processed or assembled in China. "China is widely recognized to be the biggest source of the problem", the official added.
Trade experts and business leaders said the new investigation into intellectual property could be a sign that the trade agenda is shifting into the hands of a respected negotiator, U.S. Trade Representative Robert E. Lighthizer, who during the Reagan administration helped implement some of the most protectionist trade policies of recent decades.
Should Lighthizer decide to launch such an investigation, "he will have at his discretion broad powers to use all applicable measures, including, but not limited to, Section 301 of the Trade Act of 1974, which provides a basis for addressing technology transfer practices that may be harming the USA economy, exports and American jobs", an administration official said.