The charge comes following Cardiff's damaging 4-0 defeat at Sunderland last Sunday, a result that left the Welsh club bottom of the Premier League and two points adrift of safety with as many games to play.
Cala, who joined Cardiff from Sevilla in February, was sent off in the loss at the Stadium of Light, receiving a straight red card and conceding a penalty just before half-time for pulling back Sunderland striker Connor Wickham.
The Spaniard will miss Cardiff's crucial last two games as a result of that dismissal, and looks set to face further punishment from the FA after receiving a charge following an incident near the tunnel after the end of the game.
A statement on the FA website 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."
Cardiff will be relegated from the Premier League if they fail to beat Newcastle United on Saturday and either Norwich City or Sunderland win their games with Chelsea and Manchester United respectively.
Ole Gunnar Solskjaer's men will also succumb to the drop with defeat at St James' Park and a Fulham victory at Stoke City.
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