Cala - signed from Sevilla in February after becoming a free agent when buying out his contract - was shown a red card by referee Phil Dowd for pulling back Connor Wickham as the Sunderland striker looked to get clear on goal.
The Spanish centre-back is then alleged to have been involved in an incident as he went down the tunnel at the Stadium of Light.
A statement from the FA read: "Cardiff City's Juan Cala has been charged by The FA following his side's game against Sunderland on 27 April 2014.
"The charge is in relation to an alleged incident in or around the tunnel area after the end of the fixture, which amounts to improper conduct.
"Cala has until 6pm on 1 May 2014 to respond to the charge."
Having already been set to serve a suspension for the Barclays Premier League match at Newcastle, should the charge be proven, then Cala would also miss the final game of the Bluebirds' season, at home to Chelsea.
Cardiff are currently bottom of the table and could be relegated if other results go against them this weekend.
- Sports & Recreation
- Juan Cala
- Connor Wickham
- Cardiff City