Washington "cannot push China too far" and must avoid a situation that "spins out of control".
The trade talks are the result of an agreement last month between U.S. President Donald Trump and Chinese President Xi Jinping to stop the tit-for-tat tariff conflict between the two countries for 90 days starting on New Year's Day.
No details were immediately announced, but stocks rose after talks planned for two days were extended to three.
"These issues are much more hard to solve immediately but are, frankly, much more compelling to USA companies", said Jake Parker, vice president for China operations of the U.S. -Chinese relations for years.
But the statement did not say if the two sides have reached any agreement during the talks that concluded on Wednesday.
Beijing has tried to defuse pressure from its trading partners for more sweeping changes by offering concessions on investment regulations and stepping up purchases of American soybeans, natural gas and other exports.
Chinese officials have suggested Beijing might alter its industrial plans, but they reject pressure to abandon a strategy seen by communist leaders as a path to prosperity and greater global influence.
China and the U.S. wrapped up three days of trade talks and are reportedly coordinating how to characterize the results publicly as officials from both nations expressed optimism that progress had been made.
The current trade round coincided with an unannounced visit from North Korean leader Kim Jong Un, who arrived in Beijing on Tuesday for talks with Xi, ahead of a possible second meeting between Kim and Trump. It has said China's companies are treated unfairly in USA national security reviews of proposed corporate acquisitions, though nearly all deals are approved unchanged.
Meanwhile, confirming the conclusion of the trade talks, China's foreign ministry spokesman Lu Kang told a media briefing that "the extension of the talks indicates that both sides are serious about this consultation".
America is seeking assurances that China will buy more products from the U.S.in order to reduce the trade deficit, and it wants a fairer playing field for USA companies that do business inside China, NPR has reported.
Also, if Washington refuses to extend the Iranian crude oil import waivers it granted in November to eight large buyers-including China and India-they will need an alternative source of crude and it might just be the United States. Both sides have provided scant information about their discussions.
This week's talks went ahead despite tension over the arrest of a Chinese tech executive in Canada on USA charges related to possible violations of trade sanctions against Iran.
The U.S. team is led by Deputy U.S. Trade Representative Jeffrey Gerrish, and includes under secretaries from the U.S. Departments of Agriculture, Commerce, Energy and Treasury, as well as senior officials from the White House.
Trump imposed tariff increases of up to 25 per cent on $250 billion U.S. in Chinese imports.
China responded by imposing penalties on $110 billion of American goods, slowing customs clearance for United States companies and suspending issuing licenses in finance and other businesses.
Trump has been demanding China to drastically reduce the United States dollars 375 billion trade deficit and ensure IPR production for U.S. technology and services.
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Protesters wearing yellow vests take part in a demonstration by the "yellow vests" movement in Paris on January 5, 2019. The SCSI-CFDT police union said the funds should be seized to compensate the two officers injured in Saturday's attack.