Prosecutors in Manhattan have ordered the Trump inaugural committee to hand over documents relating to how the team raised and spent over $100m (£77m).
The subpoena requests a wide range of data regarding who donated to the inauguration, whether they were non-US citizens, and how the money was spent.
White House spokeswoman Sarah Sanders told CNN on Tuesday that the order has “nothing to do with the president”.
The subpoena, which has not been made public, does not allege any wrongdoing.
“We have just received a subpoena for documents,” a spokeswoman for the Trump inaugural committee told US media.
“While we are still reviewing the subpoena, it is our intention to co-operate with the inquiry.”
According to federal election law, foreign nationals are prohibited from donating to a US inaugural committee.
The investigation is separate from special counsel Robert Mueller’s probe of possible Trump campaign ties to Russia, an investigation that has led to several indictments and guilty pleas.