She said the U.S. tariff hike and a retaliatory move by China would trigger an economic downturn because of instability in commodities and financial markets, while company moves to adapt would put pressure on global growth.
German automakers Daimler (DDAIF) and BMW (BAMXF), which export high-end vehicles to China from their U.S. plants, said previous year that Chinese tariffs on American-made cars were hurting their profits.
"He is optimistic" about the talks with China, said Republican Senator Tim Scott, who was in the meeting.
The soybean market is a case in point.
USA companies would capture only 6% of the $250bn of the affected Chinese exports, while Chinese firms would retain 12%, despite the higher cost of trade, the study said. "That's going to make our farmers very happy".
Trump said he does not blame China for taking advantage of the USA but "our leaders and representatives for allowing this travesty to happen".
In a normal year China buys about 35 million tons of soybeans from the U.S. So far this year China's purchases have been 20 percent of what they were in the last marketing year, according to John Newton, chief economist at the American Farm Bureau.
The fact it contained no commitment to drop China's retaliatory tariffs left one person close to the talks grumbling the offer embodied how China is maintaining its leverage over Trump.
'We have a thing called the telephone and other means of talking.
China and the United States have been engaged in a trade war since Trump announced last June that $50 billion worth of Chinese goods would be subject to 25 percent tariffs in a bid to fix the US-Chinese trade deficit.
"Our analysis shows that while bilateral tariffs are not very effective in protecting domestic firms, they are very valid instruments to limit trade from the targeted country", Pamela Coke-Hamilton, head of UNCTAD's worldwide trade division, said in a statement.
The higher cost of US-China trade would prompt companies to shift away from current east Asian supply chains, but report suggests it's unlikely that US firms would pick up that business.
Trump has repeatedly denigrated past presidents' efforts to deal with China.
But there are also questions over the form any agreement will take and how enduring it may be. One US official said the two countries were working to set up a meeting between Xi and Trump at the end of February.
In the speech, Mr Trump also took a swipe at the trade policies of previous administrations. What comes of any deal will depend on the political will of future presidents to use the same tariffs Trump has employed to enforce it, the official said.
However, Mnuchin said the U.S. economy was "still very strong", with no signs of slowing.