The government has reduced defence funding by $5.5 billion over the next four years to help return its budget to surplus.
The opposition says that decision has taken defence funding to its lowest level, as a proportion of GDP, since 1938.
US assistant secretary of state for East Asian and Pacific Affairs Kurt Campbell has expressed happiness with the trajectory of the US-Australia alliance but concern about Australian defence spending, Fairfax Media reported on Saturday.
That concern would be raised at the Australia-US Ministerial (AUSMIN) consultation in Perth next Wednesday, it said.
A spokesman for Mr Smith said the report was at odds with conversations he had with US Defence Secretary Leon Panetta before and after the May budget.
Mr Panetta had acknowledged the US and Australia, along with other nations, were facing a new fiscal reality and all of them were under pressure, he said.
As well, Mr Panetta was "absolutely convinced and persuaded" that the government's budget approach would not in any way diminish Australia's commitment to the alliance with the US.
Prime Minister Julia Gillard would not respond to questions about the issue when she arrived for a ceremony attended by the Prince of Wales and the Duchess of Cornwall in Canberra.
"I'm here to see Prince Charles," she told reporters.
Opposition defence spokesman David Johnston said once again the US had publicly acknowledged concern about drastic cuts to Australia's defence budget.
"The prime minister and the defence minister need to take this criticism from a valued ally and partner seriously and realise they simply cannot keep using the defence portfolio as an ATM without consequences," he said in a statement on Saturday.
However, the US is also cutting its defence spending, acknowledging funding pressures it and other nations are confronting.
Australia Defence Association executive director Neil James said there was no doubt the US was very disappointed in Australia's reduced defence spending.
"Alliance works both ways and the time to help your allies is when they most need it," he told AAP.
"Now is the time to help the Americans by not cutting our defence budget when they have to."
Mr James said some of those most upset about the government's defence cuts were Labor politicians who had worked hard for two generations to restore trust in the ALP on national security.
"They have seen it blown away in a very short period for no real reason except factional and personal advantage within caucus."
Defence Minister Stephen Smith has dismissed reports the Obama administration is concerned about big spending cuts the Gillard government has made to defence.