He said a USA declaration of Chinese manipulation could jeopardize talks with China on North Korea.
Trump hailed China's abstention.
On Syria, Xi said that any use of chemical weapons is unacceptable and that the path of political settlement should be followed. And neither shows any sign of responding positively to the White House's newly forthright posture.
As for North Korean leader Kim Jong Un, Trump said he's "doing the wrong thing" with his ongoing nuclear testing and saber-rattling.
On Tuesday, Trump tweeted that he'd told Xi a trade deal with the USA would be "far better for them if they solve the North Korea problem". If only the US could compel China to drive North Korea to the negotiating table over its nukes program. Xi then patiently explained Chinese-Korean history to Trump - who then promptly changed his mind.
"What I did should have been done by the Obama administration a long time before I did it, and you would have had a much better - I think Syria would be a lot better off right now than it has been", he said.
Trump and Xi spoke by telephone Tuesday night, just days after their two-day gathering at the president's Mar-a-Lago resort in Florida.
Dems ask Federal Bureau of Investigation to suspend Kushner's security clearance
Knowingly falsifying or concealing information on a SF-86 questionnaire is a felony, punishable by up to five years in prison. The president fired his National Security Advisor, General Michael Flynn , for lying about foreign contacts.
As Vox writer Zack Beauchamp pointed out, Trump's words are troubling for a number of reasons. The Guardian and other news outlets reported that North Korea is "primed and ready" to conduct the country's sixth nuclear test since 2006.
The two leaders exchanged views on issues of mutual concern including the situation on the Korean Peninsula. That led to last week's summit.
And before that, Secretary of State Rex Tillerson said that "all options are on the table" as the Trump administration calculates how to deal with the threats North Korea poses to its neighbors and, potentially, the United States. China helped North Korea fight a US -led coalition to a stalemate in the Korean War and remains the isolated nation's principal trading partner. "Maybe he didn't like me but I think he liked me ... we understand each other".
The biggest potential flashpoint is nuclear-armed North Korea, a rogue state that exists in nearly complete isolation - except for its tight relationship with China.
In another surprising stance towards China, the U.S. president also refused to accuse Beijing of manipulating the currency. One of Trump's foremost campaign pledges was to punish China early in his presidency for depressing the value of its currency in order to boost exports and maintain a trade surplus with the U.S. In a single week, the administration has given Moscow and Beijing ultimatums on Syria and North Korea, along with threats to "go it alone" if they don't fall in line with USA strategy. While widely read in China and run by the ruling Communist Party's official People's Daily, the Global Times does not represent government policy. The Trump administration is considering tougher economic sanctions, including an embargo on oil supplies to North Korea, flight bans, cargo interception and punishment on Chinese banks doing business with North Korea, Reuters reported Thursday, citing unidentified US officials.
Beijing says it will not countenance measures that could bring about a collapse of the regime that could release a flood of refugees across its border, destabilize northeast Asia and result in a USA -friendly government taking power in Pyongyang.