Chinese President Xi Jinping (R) and US President Donald Trump at the Great Hall of the People in Beijing on November 9, 2017.

Scheduling for the next round of negotiations is "in flux" because it is unclear what the two sides would negotiate, two sources briefed on the status of the talks said. China has not signaled it is willing to revisit past promises on which it reneged earlier this month, despite showing up for talks in Washington last week.

Negotiations between the U.S. and China appear to have stalled as both sides dig in after disagreements earlier this month.

Both sides have dug in on their positions this week. China propped up its currency and cut U.S. pork orders, while state media took on an increasingly nationalistic message. The Trump administration, meanwhile, put Chinese telecommunications company Huawei and its affiliates on a business blacklist and banned it from the supply chain, actions it had shelved earlier in the trade talks to smooth relations.

China has invited the U.S. delegation to Beijing, and earlier this week, Treasury Secretary Steven Mnuchin appeared open to accepting the offer. But sources say scheduling discussions have not taken place since the Trump administration ratcheted up its scrutiny of Chinese telecom companies. The move was seen as a shot across the bow.

The White House, Office of the U.S. Trade Representative and Treasury Department did not immediately respond to requests to comment.

Stocks dipped after the report that trade discussions have stalled. The three major U.S. indexes all closed lower Friday.

President Donald Trump on Friday again said the world's two largest economies came close to a trade agreement before China backtracked.

"We actually had a deal and they broke it, OK?" the president told the National Association of Realtors.

A spokesperson for China's Foreign Ministry said that China prefers to resolve disputes through dialogue. The countries' two presidents have been in touch, the spokesman said, but the U.S. overall has been "insincere" in its position.

"Words must be matched with deeds," spokesperson Lu Kang said at a daily briefing.

Reacting to U.S actions on Huawei, China's Commerce Ministry said in a statement, "We firmly oppose the act of any country to impose unilateral sanctions on Chinese entities based on its domestic laws, and to abuse export control measures while making 'national security' a catch-all phrase. We urge the US to stop its wrong practices."

Last week, the U.S. increased tariffs on $200 billion in Chinese goods. China retaliated by raising duties on $60 billion in American products.