Both presidents struck a diplomatic tone in their remarks.
Trump said his meeting with Xi was "excellent ... as good as it was going to be."
He made the brief remarks seated next to Turkey's President Recep Tayyip Erdogan during a quick media spray.
"We discussed a lot of things and we're right back on track and we'll see what happens, but we had a really good meeting," Trump said. "I think President Xi will be putting out a statement ... and we will too."
He added: "We had a very, very good meeting with China, I would say probably even better than expected. The negotiations are continuing. ... We're doing very well."
Trump was complimentary of Xi in brief remarks before the private meeting, saying, "We've become friends," and recalling his trip to Beijing in November 2017 as "one of the most incredible of my life."
"I look forward to working with you," Trump said. "We've had an excellent relationship but we want to do something that will even it up with respect to trade."
The president said it would be historic if the two sides could reach a fair trade deal and expressed optimism that the meeting would bring a positive result.
"I think this can be a very productive meeting and I think we can go on to do something that will be monumental and great for both countries and that's what I look forward to doing," Trump said.
Xi began his comments by harking back to the days of so-called ping-pong diplomacy that began a process of normalizing relations between the two sides.
"The small ball played a big role in moving world events," Xi said.
"Enormous change has taken place in the international situation and U.S.-China relations, but one basic fact remains unchanged: China-U.S. relations benefit from cooperation and lose in confrontation," Xi said.
"Cooperation and dialogue are better than friction and confrontation," Xi continued, and then referenced his recent exchange of calls and letters with Trump and said he looks forward to the meeting to forge a way toward cooperation.
Trump did not take any questions about whether they would be discussing the controversy surrounding Chinese telecom giant Huawei or whether the U.S. and China are close to a trade deal.