The Elysee Palace's service responsible for correspondence received a letter in the mail that contained a severed human finger on July 9-10, French media cited sources as saying.
The finger was "put in the refrigerator where the police keep their food," the report said, adding it was unknown why the finger had been sent.
The man whose finger was in the letter has already been found, and "appropriate services will take care" of him, media reported.
The Elysee Palace did not release a statement on the matter to French media.