Ahead of what was seen as the most important meeting of USA and Chinese leaders in years, both sides said differences remained, and the outcome of the talks were uncertain.
USA companies and consumers are bearing part of the cost of the US tariffs on China by paying higher prices for goods, and many companies have increased prices of imported goods.
In other business, the United States and China reached a 90-day ceasefire in a trade dispute that has rattled financial markets and threatened world economic growth.
Trump and Xi were set to talk over dinner Saturday at a summit of world leaders in Argentina. It was agreed in the truce only that the USA will not raise tariffs a further 25 per cent on Jan 1, and the negotiation window is for only 90 days.
The U.S. and China have agreed to a 90-day truce in a bid to work out their trade differences. The deal amounts to a ceasefire in the series of escalating, tit-for-tat tariffs the US and China have imposed on each other's goods throughout the year.
It noted also that China did not mention U.S. calls for deep structural changes in its economic policies.
What they agree on - or do not - will likely determine whether stock markets rise or fall and whether the world economy gets some relief from destabilizing trade tensions, as well as cast judgement on the wisdom of the USA leader's hard-nosed trade tactics.
Speaking to reporters on Air Force One, Trump hailed his agreement with Xi.
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"The United States has no proof that most fentanyl in the country comes from China", he said.
A statement from White House press secretary Sarah Sanders noted that China has agreed to start purchasing agricultural products from U.S. farmers "immediately".
And that is important for President Trump as Chinese tariffs were affecting his power base, the rural heartlands of the Midwest which export commodities like soya beans and sorghum to China.
The United States and China are locked in a dispute over their trade imbalance and Beijing's push to challenge American technological dominance. "During the past 40 years, with the support of the global community, we in China have forged ahead with perseverance and made historic achievements in development", said Xi.
Beijing hopes to persuade Trump to abandon plans to hike tariffs on $200 billion USA of Chinese goods to 25 per cent in January, from 10 per cent at present.
"The world is undergoing a hard moment as Trump pursues a vision at odds with the idea of collective action on trade and climate change", EU President Donald Tusk said at the G20.
Trump also held "informal conversations" with Russian President Vladimir Putin and other leaders on the sidelines of the G20 summit on Friday night. Argentina's security minister said eight gasoline bombs were discovered in an area of the capital several miles from the summit venue where a protest in the afternoon drew thousands of demonstrators who held up banners with slogans like "Go away G-20" and "Go away Trump".
In what the White House called a "wonderful humanitarian gesture", the White House said that Xi would crack down on fentanyl, the opioid painkiller largely made in China that is behind an epidemic of USA overdoses.
The "coalition" against the United States on climate change was beginning to fray, a senior White House official said, adding that several countries, including Turkey, Russia and Saudi Arabia, had balked at signing the document before finally backing it. President Trump expressed his friendship and respect for Chairman Kim.