China and the United States will come up with a new trade deal within 90 days after a "highly successful" meeting between Donald Trump and Xi Jinping.
Scott Morrison got his trade point across at the G20 but ongoing tensions between China and the US watered down the summit's key messages.
The group of nations agreed to reform the World Trade Organisation, just two weeks after the US and China could not agree on it at another key summit.
But the G20's annual commitment to fighting protectionism in the global economy was missing, as the US and China continued to slap tariffs on each other.
"Sometimes the progress is made simply by bringing issues to a head," Mr Morrison told reporters before leaving Buenos Aires on Saturday local time.
After the G20, President Trump and President Xi met for more than two hours and promised to come up with new rules on technology theft, intellectual property, services and agriculture.
If the deal isn't complete within 90 days, tariffs on Chinese products into the US will jump from 10 per cent to 25 per cent.
China will also purchase goods from the US in a bid to reduce the trade imbalance between the two countries.
"This was an amazing and productive meeting with unlimited possibilities for both the United States and China," President Trump said in a statement.
Australia got a commitment from all nations to work on reforming the WTO to better deal with the digital economy and disputes between nations.
The official communique also committed countries to dealing with climate change, except for the United States, which reserved its right to use all energy sources to pursue economic growth.
But for the first time in 10 years the G20 did not explicitly condemn protectionism.
"I think this is actually a sign we're moving on from those ideological discussions," Mr Morrison said.
"I don't think anybody is about protectionism."
Mr Morrison and Dutch Prime Minister Mark Rutte also spoke about the ongoing grief their two countries share from the MH17 disaster.
Australia and the Netherlands led the investigation into the shooting down of the Malaysia Airlines flight over the Ukraine in 2014, which killed citizens from both countries.
"I once said the only positive coming out of the terrible tragedy of MH17 is the strong bond between Australia and the Netherlands," Mr Rutte said.
"How are the families in Netherlands today?" Mr Morrison asked him.
"It's difficult, some of them are in really bad shape, some are trying to get on with life," Mr Rutte replied.
Mr Morrison also met earlier with United Kingdom Prime Minister Theresa May, whom he praised for handling the tough Brexit negotiations.
