The incident is alleged to have taken place at the White House Correspondents' Dinner on Saturday (April 28).
Cindy Adams, a columnist for the New York Post, claims that Lohan visited the bathroom a few times during the dinner for a cigarette.
"[Lohan] said she doesn't usually smoke but is boning up on it to prep for her Elizabeth Taylor role," Adams reported.
On one of the visits, the Mean Girls actress apparently said to an elderly Hispanic lady named Bianca, who was cleaning the room: "You're too old to be doing this."
Lohan then tried to give the woman a $100 note from her purse, but the attendant backed away, saying: "No, no, no."
The actress was said to have persisted, repeating that the woman was too old for that kind of work, and Bianca eventually accepted it.
Lohan was previously reported to have missed her planned flight to Washington DC for the dinner because she "couldn't pull it together".