US stocks were lower Monday in anticipation of the new tariffs.
"That's why we continue to urge everybody, whether they are those who engage in market distorting subsidies, or whether they are those who might talk about or pursue multi-lateral tariff actions, to think carefully about the consequences of doing so". "We have been very clear about the type of changes that need to be made, and we have given China every opportunity to treat us more fairly", he said.
So far in an ongoing trade war, China has matched new U.S. tariffs on goods.
He described the trade dispute with China in grave terms.
"As President, it is my duty to protect the interests of working men and women, farmers, ranches, businesses, and our country itself", Trump said in a statement.
They include consumer products such as luggage and handbags, textiles including cotton and other fabrics, household items such as cutlery and towels, and food including rice.
The latest round of imports will face 10 percent tariffs through the end of the year, and then the rate will jump to 25 percent, giving businesses time to find new suppliers, officials said. He's poised to extend tariffs of 10-to-25 percent on another $200 billion.
The phase-in was created to give US companies more time to adjust their supply chains, according to senior administration officials.
"If sentiment around the talks is positive, the tariffs may be viewed as a pillow fight between the USA and China-lots of swinging but no real damage", Steve Englander, head of Group of 10 currency research at Standard Chartered, said in a note.
"The reality is you can not permit the theft of intellectual property", Kudlow emphasized.
U.S. companies have already said they are anxious about the effect of higher costs on their businesses.
Trump has also complained about America's gaping trade deficit - $336 billion a year ago - with China, its biggest trading partner.
The administration teed up the steep new duties months ago. Mark Vena, an analyst with technology research firm Moor Insights & Strategy, told the Wall Street Journal today that Apple has the inventory of key components for products, like the iPhone, to get through the holiday but the threats of retaliation by China "could be a serious problem" later on.
China has said it will retaliate.
Farmers, manufacturers, retailers and other industry groups have formed a coalition to oppose the tariffs, calling them taxes on American families. The US also asserts that Beijing uses state money to buy American technology at prices unaffordable for private companies. "Thus, we had to shake things up to stop this inequitable evolution", he said. The Office of the US Trade Representative concluded after an investigation that China's tactics range from requiring US and other foreign companies to hand over technology in return for access to the vast Chinese market to outright cyber-theft.
The tariffs on the US$200 billion list will start on September 24, according to a senior United States administration official.
China had previously vowed to retaliate further against any new USA tariffs, with state-run media arguing for an aggressive "counterattack".
In the latest iteration, almost half of Chinese imports face tariffs, including consumer products that range from furniture to building products and seafood. The revisions were made in response to thousands of written comments and hours of public testimony.
European share markets followed Asian counterparts lower on Monday as investors took fright at news Washington was set to announce a new round of tariffs on Chinese goods.