In its response to the federal government's proposed digital duty of care laws, the Trump administration said it had serious concerns with the laws, urging for American-based platforms to be exempted.
"A framework that empowers governments to enforce vague definitions of 'harm' risks becoming a mechanism for viewpoint-based censorship," the US government said in a statement posted on the American embassy to Australia website.
"Platforms will be incentivised to over-moderate speech that should be protected to avoid regulatory penalties."
Under the digital duty of care, users on social media will have the option to remove an algorithm-driven feed and instead default to seeing content from people they follow directly.
Tech platforms would also be forced to protect under-18s from harmful posts such misogynistic content, pornography, posts that encourage eating disorders or content that glorifies crime.
The eSafety commission would also have powers to issue removal notices to social media platforms.
Prime Minister Anthony Albanese introduced the proposal in early September, releasing a draft for consultation.
But the US government said Australia needed to determine how the harm and risks would be determined and whether standard definitions would be needed.
The statement said calls to filter content would not be different than outright removal.
"The US government would likely consider such a measure as facilitating censorship," it said.
"We ask that Australia withdraw any plans to mandate that platforms algorithmically suppress content based on ambiguous, government-defined safety criteria."
The US had called for the federal government to explain its response to industry concerns, and how the definitions of what constituted harmful content would be determined.
The statement said US companies would be disproportionately impacted by the measures.
"The large majority of social media and video-sharing platforms that would be affected are US-headquartered companies, operating substantially on US soil and serving American users alongside Australian ones," the statement said.
The statement was made hours before Mr Albanese was due to speak at an event at the UN General Assembly on protecting children online.
Mr Albanese will address the Coalition for Children's Rights and Protection in the Age of AI, alongside French President Emmanuel Macron and Spanish Prime Minister Pedro Sanchez.
The prime minister will say the digital duty of care laws built on the world-first reforms in Australia that banned under-16s from having social media accounts.
"Australia is now introducing additional laws ... to put choice back into the hands of Australia over the algorithm," Mr Albanese will say.
"They will make social media platforms give people the choice."
The prime minister also discussed the social media measures with former Apple chief executive Tim Cook at the tech giant's California headquarters on Sunday.
The pair had a one-hour, closed-door meeting, after Mr Cook extended an invitation to the prime minister, following a conversation over the phone on child safety measures on Apple devices.
Some such measures were inspired by the social media ban.
Mr Albanese will tell the UN coalition the social media ban was showing results.
"Our ban gives our children precious breathing space in which to mature and make safer social media decisions," he will say.
"We must give children back their childhood. The ban is making a difference."
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