The Federal Reserve Bank of New York sold euros for yen on behalf of the Treasury through Goldman Sachs and Morgan Stanley on Friday, the FT said, citing people familiar with the matter.
The report did not indicate any amounts of yen purchased.
Earlier on Friday, the Treasury informed a number of banks that it might intervene in the yen market and they should "stand ready for future action", a source familiar with the matter told Reuters.
A Reuters photo of Treasury Secretary Scott Bessent's notepad during a cabinet meeting at Camp David in Maryland showed the words "To Do", followed by "Buy Japanese Yen (JPY) $US5-10 bil".
The Treasury did not immediately respond to requests for comment on the FT report and the Bessent notepad photo.
The New York Fed and Morgan Stanley also did not immediately respond to requests for comment outside regular business hours.
Goldman Sachs declined to comment.
The US last directly supported the yen in 2011, co-ordinating with fellow Group of Seven nations to stabilise markets after Japan's earthquake and tsunami disaster.
News of the potential intervention by the Treasury helped boost the yen, with a notable jump during late afternoon trading.
The dollar dropped to about 157.6 yen just before 5pm, Washington time, from about 158.9 yen at 4.14pm, LSEG data showed.
The US currency had risen in recent weeks to nearly 164 yen, its highest since 1986.
Japan might have sold as much as $US58.97 billion ($A84.34 billion) to buy yen on Thursday, central bank data indicated on Friday, signalling its repeated efforts to stem the yen's weakness.
Tokyo intervened again in New York trading hours on Friday, the Nikkei reported on Saturday.
Finance ministry officials could not immediately be reached for comment outside working hours, but the ministry, in an apparent effort to soothe market worries about the limits of Japan's firepower for large-scale intervention, posted on X that Japan's monetary authorities have "a broad range of tools to address market liquidity needs".
