Mr Morrison said the G20 was a “critically important” meeting given the concerns about trade and the economy.
“It is about the two biggest economies addressing their differences to provide certainty and stability to the global economy,” the Prime Minister said.
“We need them to agree a constructive way forward on global trade.”
The Prime Minister said he had acted “as a friend and partner of both countries” to encourage them to settle their disagreements at the East Asia Summit in Singapore and the Asia Pacific Economic Co-operation meeting in Port Moresby earlier this month.
Mr Morrison said it would be an “own goal” if the trade tensions continued.
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“My key message at the G20 will be that to enjoy the prosperity, security and connectedness we have today, we must protect the international system,” Mr Morrison said.
“That system is built on rules and openness. As Prime Minister I will prosecute this case again at the G20, as I did at the APEC and [East Asia] summits.”
In a blow to Australian hopes of any detailed discussion with Mr Trump, the summit will not include a formal bilateral meeting between the US President and Mr Morrison.
The government says the close relationship between Australia and the US, along with the fact that Mr Morrison spoke to US Vice-President Mike Pence this month, means there is no pressing need for a formal bilateral with Mr Trump.
The Turnbull government secured an exemption from the Trump administration’s tariffs on steel and aluminium, setting Australia apart from other nations at the G20 that have unresolved trade disputes with the US.
Mr Morrison arrives in Buenos Aires on Thursday night, local time, for two days of meetings before flying home for Parliament next week.
The Argentine government has encouraged its citizens to leave the city over the next few days to ease pressure around an event that is already attracting vocal protests.
The host, Argentine President Mauricio Macri, will also have to manage a potential legal challenge to the Saudi Arabian crown prince, Mohammed bin Salman, who is attending the summit weeks after his agents murdered journalist Jamal Khashoggi.
An Argentine prosecutor has prepared a charges against the crown prince for breaching human rights law but this is not expected to get around the diplomatic immunity extended to those attending the summit.
Mr Morrison said the danger to the world economy should be taken seriously.
“We cannot pretend that ongoing trade tensions do not pose real threats to the global economy,” he said.
“The G20 has a good history of dealing with serious economic issues.”
David Crowe is the chief political correspondent for the Sydney Morning Herald and The Age.
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