The deal amounts to a ceasefire in the series of escalating, tit-for-tat tariffs the USA and China have imposed on each other's goods throughout the year.
Meanwhile Wang Xiaolong, director general of the Foreign Ministry's department of global economic affairs, said negotiations between Chinese and United States officials were making some progress.
But financial markets, spooked by the potential impact on the world economy, hoped that at least some kind of truce could be declared.
Thaw in China-U.S. relations?
China's efforts to tackle the abuse of fentanyl-like substances have won positive comments from across the globe and Beijing has chose to list all fentanyl-like substances and their precursors as controlled substances, Wang said.
China and the United States have agreed to halt additional tariffs as both countries engage in new trade negotiations with the goal of reaching an agreement within 90 days, the White House said on Saturday.
"Cooperation is the best option for the two countries" in promoting world peace and prosperity, Xi reportedly told the U.S. president at a working dinner, according to Xinhua. "Only with cooperation between us can we serve the interest of both peace and prosperity", he said.
G20 delegates said negotiations on the summit statement proceeded more smoothly than at a meeting of Asia-Pacific leaders two weeks ago, where disagreement on protectionism and unfair trading practices prevented a consensus.
Bowing to the view of Trump's administration, the G20 said that multilateral trade was "falling short of its objectives" on promoting growth and job creation.
But the USA reiterated its withdrawal from the agreement, "and affirms its strong commitment to economic growth and energy access and security".
Paul Ashworth, chief US economist at Capital Economics, notes that if talks fail, tariffs would rise on the $200 billion of goods already on the receiving end, and would be imposed on the remaining $250 billion that are, so far, penalty-free. Once that 90 days is up, the 10% tariffs will increase to 25% if no agreement has been reached. China has retaliated with tariffs on $110 billion worth of US imports.
A senior U.S. official told Reuters that it was the first time that the G20 had recognised that the WTO was "currently falling short of meeting its objectives" and needed reform.
At the same time, USA farmers have been hurt by reduced Chinese imports of soybeans and other products.
If he can not get a deal with Xi, he has vowed to more than double most of those tariffs on January 1 and he has threatened to expand tariffs to virtually everything China ships to the US.
The end of Trump's latest tense foray into global diplomacy comes as America prepares to say a final farewell to former president George H.W. Bush, who died on Friday at the age of 94.
"He was a terrific guy and he'll be missed".
Trump said that "the very important meeting" with Xi would go on, but he noted that Bush's death "really puts a damper on it, to be honest with you". "We will review progress at our next Summit", the communique said.
"It's an incredible deal", Trump told reporters aboard Air Force One, on his way back to Washington.
Other attendees on the U.S. side included Treasury Secretary Steven Mnuchin, Secretary of State Michael Pompeo, U.S. Trade Representative Robert Lighthizer, China hawk and senior adviser Peter Navarro, National Security Adviser John Bolton and Trump's son-in-law, Jared Kushner, who's a senior adviser to the president.
Trump also suggested that following their talks, President Xi could now approve a deal for Qualcomm to buy chip rival NXP.
The acquisition collapsed four months ago after Chinese regulators expressed anti-trust concerns.