Xi urged the two countries to step up coordination in multilateral mechanisms including the G20 and BRICS, and unite all parties concerned in upholding multilateralism, safeguarding the core values and basic rules of the World Trade Organization, supporting trade liberalization and facilitation, and opposing protectionism and unilateralism.
The meeting between the two - known in diplomatic terms as a "pull aside" - followed a meeting between Trump and prime ministers of Japan and India on the sidelines of the summit.
Kirill Dmitriev, the chief of Russia's sovereign wealth fund, told reporters that Putin would meet the prince Saturday and discuss boosting Saudi Arabia's $2 billion investment in Russian Federation.
A CNBC contributor on global trade says that "Peter at dinner is not a good sign" for any speedy resolution to the U.S.
"Even though the agenda that brings us together today is different, I'd like to ask you to act with the same sense of urgency that brought us together in 2008".
British Prime Minister Theresa May's attendance at the summit marked the first time a United Kingdom prime minister has visited Argentina's capital.
U.S. Trade Representative Robert Lighthizer said Wednesday that Trump ordered a new review on the auto trade war with China. "Way, way, way above my pay grade", he said.
In his latest attack, Mr Trump pointed to the 25% duty on imported pickup trucks and commercial vans from markets outside North America as supporting the industry.
In November, Asia Pacific Economic Cooperation officials gathered in Port Moresby, Papua New Guinea, failed to issue a joint statement for the first time ever after the United States and China delegations clashed over language addressing trade and security.
"Not just in various strategic co-operation but economically, and the people-to-people relationships, well, there's none better", he said.
But a day before the three neighbors were due to formalize the agreement on Friday, negotiators were still thrashing out what exactly they will be putting their names to, officials said on Thursday.
He said the European Union is expected to extend sanctions on Moscow over its "totally unacceptable" seizure of Ukrainian ships and their crews near the Crimean Peninsula.
The pair discussed trade, co-operation in the Pacific, and the security situations in Iran and North Korea. "We'll see what happens".
Asked about the European concerns, a U.S. official said progress was being made on the joint statement and the White House was "optimistic" about the document as a whole.
Saudi Arabia's delegation is headed by Crown Prince Mohammed bin Salman, who was greeted by world leaders including Vladimir Putin and Emmanuel Macron on day one. The Saudi foreign ministry said the prince had meetings with his French, South Korean and Mexican counterparts.
Saudi Arabia has denied that bin Salman played a role, but some leaders may be cool toward him to avoid seeming to legitimize a man who US intelligence agencies concluded ordered the killing.
The G20 summit is the biggest global gathering in Argentina's history, and the protest underlined security concerns after recent football violence forced the relocation of a showpiece final to Spain.
Trump's skepticism that global warming is caused by human activity has raised questions about whether the countries will be able to reach enough consensus on climate change to include it in the summit's final communique.
Their embrace comes amid reports that Russian Federation and Saudi Arabia have reached a pact to cut oil production when the OPEC cartel meets on December 6 in Vienna, to help shore up collapsing crude prices.
The first ladies arrived in Buenos Aires, Argentina on Thursday, ahead of this weekend's G20 summit.
The Chinese leader said that Beijing wants to hold the G20 nations together - a remark that came despite the deep divide between the USA and China.
The three countries agreed a deal in principle to govern their trillion dollars of mutual trade after a year and a half of contentious talks concluded just an hour before a deadline on September 30.
Trudeau still had a few barbs on Friday. Washington accuses China of deploying predatory tactics in its tech drive, including stealing trade secrets and forcing American firms to hand over technology in exchange for access to the Chinese market.