Labor has accused Scott Morrison of "megaphone diplomacy" during his visit to the US and of taking potshots at Australia's largest trading partner.
The prime minister landed in the US at a time of acute trade tensions between the world's largest economy and China.
Mr Morrison and US President Donald Trump both called for global institutions to treat China as a developed country, saying the world's second-largest economy is clearly no longer of developing status.
Deputy Opposition Leader Richard Marles disagrees, saying China is still a developing economy under WTO rules, "that is the matter of fact".
US President Donald Trump and Prime Minister Scott Morrison at the opening of Pratt Paper Plant in Wapakoneta, Ohio. Source: AAP
"From an Australian point of view, that's something that we should be negotiating and working through with China in a respectful way," he said.
"Now, what we saw this week was the prime minister in the United States in the context of there being trade tensions between the US and China and from there taking potshots against that."
Mr Marles, who is also Labor's defence spokesman, was in China last week delivering a speech to the Beijing Foreign Studies University at the same time Mr Morrison was being feted by President Trump.
During that speech, Mr Marles called for stronger defence co-operation between the two countries.
Deputy Opposition Leader Richard Marles has accused the prime minister of engaging in "megaphone diplomacy" during his visit to the US. Source: AAP
He said while such co-operation already exists, it is any area where there is an opportunity to build greater trust between the two countries,
"Right now, we have a massive trust deficit in terms of our relationship with China, and we need to build trust," he said.
