Ahead of the G20, Mr Trump had told US media he expected to go ahead with plans to raise tariffs on $200bn (£157bn) of Chinese goods - first introduced in September - from 10% to 25%, starting in January.
In return, the White House adds, China agreed to buy an unspecified but "very substantial" amount of agricultural, energy, industrial and other products.
Chinese state TV said earlier: "No additional tariffs will be imposed after January 1, and negotiations between the two sides will continue."
Both sides have imposed tariffs on billions of dollars' worth of goods. The US has hit $250bn of Chinese goods with tariffs since July, and China has retaliated by imposing duties on $110bn of US products.
Mr Trump had also said that if talks in Argentina were unsuccessful, he would carry out a threat to hit the remaining $267bn of annual Chinese exports to the US with tariffs of 10-25%.