Mexican second-division club Celaya wanted to sign Maribel Dominguez after she impressed in a trial. The 26-year-old was due to sign for the men's team this week but Fifa's executive meeting in Zurich at the weekend rejected the request from Celaya.
In a written statement, the committee stressed that "there must be a clear separation between men's and women's football. This is laid down in league football and in international matches by the existence of gender-specific competitions, and the laws of the game and Fifa's regulations do not provide for any exceptions."