Tottenham are said to be “very disappointed” and “shocked” by the decision to award midfielder Eveliina Summanen a two-match ban.
The London club unsuccessfully appealed against the charge.
It related to an incident when Summanen held her face as if struck by United’s Ella Toone, who was sent off.
A three-match suspension has since been overturned for Toone’s red card following an appeal from Manchester United.
Finland international Summanen will miss an FA Cup tie against Reading on 26 February and the WSL game at Manchester City on 5 March.
Spurs, who were “surprised” at the dismissal of their appeal, are also understood to be frustrated by a lack of consistency when applying rules in the WSL.
Manchester United boss Marc Skinner described Summanen’s role in Toone’s sending-off as “play-acting” immediately following the game.
Tottenham still supports Summanen, who denied the charge, and will continue to make enquiries into why the decision to award a two-match suspension was made.
