President Trump, according to the New York Times, is frustrated by Chinese leader Xi Jinping's failure to lean on North Korea over its missile launches.
"At the same time, bilateral relations have been affected by some negative factors". These include putting USA sanctions on a Chinese bank for dealings with North Korea, and accusing China of being one of the world's worst offenders of human trafficking and forced labor.
He warned China's president that the United States is willing to act alone in the event that China fails to "put a heavy move on North Korea".
Then last week, during an appearance with South Korea's leader at the White House, Trump mentioned that country and Japan as allies in seeking a diplomatic solution on North Korea, notably leaving out China. That's the way to end North Korea's nuclear program.
Nikki Haley, Trump's United Nations ambassador, told an emergency session of the council Wednesday that the world must do more to "cut off the major sources of hard currency to the North Korean regime".
In a show of force, South Korea and the United States also staged "deep strike" precision missile firing drills on Wednesday as a warning to the North. Thursday's drills were aimed at boosting readiness against possible maritime North Korean aggression. Japan's chief cabinet secretary, Yoshihide Suga, told reporters Monday that the pair agreed that China must be firmer with North Korea.
According to the White House statement, Trump raised the growing threat of North Korea's nuclear and ballistic arsenals with the Chinese president.
Trump has been weighing new quotas or tariffs on steel imports for national security reasons and plans to discuss his concerns at the G20.
Aston Villa sign Terry
Aston Villa have completed the signing of former Chelsea captain John Terry , with colourful club owner Tony Xia the first to welcome the ex-England skipper with a post on Twitter.
Restricting guest workers is one way the US and other countries could try to reduce North Korea's access to foreign now.
On June 20, Mr Trump had expressed his impatience and tweeted that "While I greatly appreciate the efforts of the President Xi and China to help with North Korea, it has not worked out". "Failure in the Clinton administration, failure in the Bush administration, failure in the Obama administration, all based on the same policy, that North Korea should be negotiated out of its nuclear weapons program through diplomacy and sanctions".
"The G-20 summit will provide another chance for President Xi and Trump, who have already established good personal relationship, to catch up and maybe fix things a bit".
Trump, since entering the White House, has placed a particular focus on pushing China - North Korea's biggest trading partner - to use its influence and ramp up economic pressure.
The call came at the end of a tense week in US - China relations, which analysts said signaled the end of honeymoon period between the two superpowers that began with a summit at Trump's Mar A Lago resort in April.
Other U.S. decisions have recently drawn criticism from China.
Mr Trump also spoke with Prime Minister Shinzo Abe of Japan about North Korea, and they highlighted "their unity with respect to increasing pressure on the regime to change its unsafe path", the administration said.
He said the USA would be watching what happens in the coming weeks and months but chided North Korea for "behaving in a very, very unsafe manner" and added: "Something will have to be done about it".