The group of 20 accounts for 85% of the world's GDP and two-thirds of its population.
Mr Trump and Chinese President Xi Jinping are due to meet on the sidelines of the summit in Buenos Aires.
The United States has levied additional duties of between 10 percent and 25 percent on $250 billion of Chinese goods this year as punishment for what it calls China's unfair trade practices, with the 10 percent tariffs set to climb to 25 percent next year.
"We can't resolve problems such as the future of work or climate change issues on our own", said Mr Macri.
Ahead of his visit to Argentina, the president said he would discuss with Trump the Manbij issue, a matter which continues to be an obstacle in the reconciliation of strained relations between the two North Atlantic Treaty Organisation allies despite a deal made for cooperation.
"If they don't shape up, I would withdraw from the WTO", he told Bloomberg News in August, adding that the agreement establishing it was "the single worst trade deal ever made". I think we'd like to. "And we´ll see", the president said. The United States and China are locked in a dispute over their trade imbalance and Beijing's push to challenge American technological dominance. "Way, way, way above my pay grade", he said.
On the eve of the summit, G20 member nations were still racing to reach agreement on major issues including trade, migration and climate change that in past years have been worked out well in advance.
Trump's skepticism that global warming is caused by human activity has raised questions about whether the countries will be able to find enough common ground on climate change to include it in any communique.
A Chinese foreign ministry official in Buenos Aires said there were signs of increasing consensus ahead of the discussions but that differences persisted.
"I guess when they put out blimps to make me feel unwelcome, no reason for me to go to London", Trump said of the time of the protests ahead of his visit.
Trump and Xi will be seeking a way out of a trade war between the world's two biggest economies, while also saving face for their domestic audiences at home.
The six-page draft statement says the 20 countries support the worldwide trading system but acknowledge that the current system doesn't work and needs fixing, via reform of the WTO.
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Curry also invited Riley to come to Oakland for a special event that's in the works for International Women's Day on March 8. She wrote, "I know you support girl athletes because you have two daughters and you host an all girls basketball camp".
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The United States and other countries have also criticized the Russian actions in the Kerch Strait. The Moscow Patriarchate strongly denies this and says it is working to promote peace in Ukraine .
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We need to talk about it, there is nothing that can't be solved, he said, adding that we need a big dream and political will. Punjab Cabinet Minister Navjot Singh Sidhu also attended the ceremony.
Meanwhile, two men under heavy criticism from the West lately - Russian president Vladimir Putin and Saudi Crown Prince Mohammed bin Salman - appeared to seek refuge in each other, bonding with a tough-guy hand grab as the leaders sat down for talks.
The Kremlin said it "regrets" Trump's decision to scrap the meeting.
On the trade war front, White House economic advisor Larry Kudlow said on Tuesday trade talks between the US and China have been heating up ahead of the summit.
The 20 government leaders - as well as representatives of other invited nations and global institutions - were welcomed on stage at the Costa Salguero Center, the venue for the 13th G20 summit, on the shores of the Rio De La Plata.
An Elysee official told Reuters it was the first time the two had spoken since journalist Jamal Khashoggi was murdered in October at the Saudi consulate in Istanbul.
But Human Rights Watch accuses him of responsibility and also of war crimes in Yemen, and on Wednesday, Argentine legal authorities took initial action to consider a request to prosecute him for alleged crimes against humanity.
Bin Salman told Macron not to worry, but Macron countered, "I am anxious".
Saudi Arabia has insisted the prince had no prior knowledge of the killing. Armed soldiers in military vehicles manned checkpoints leading to the summit venue and the media center some 5 kilometers away.
Uncertainty prevailed about how Trump, known for his unpredictability, would behave at what was shaping up as one of the group's most consequential summits.
There was no immediate comment in Buenos Aires from Russian President Vladimir Putin, who regards the breakup of the Soviet Union under Bush´s presidency as a historical "tragedy".
Her temporary absence could complicate French President Emmanuel Macron's attempts to build a European front against Trump at the G20.
Investors and the key United States trading partners agree that one of the main problems of the economic relationship lies in China's closed economy.
