Fernandez was harshly shown a straight red by referee Keith Stroud for a 92nd-minute challenge on Philippe Coutinho, before Dejan Lovren netted the winner three minutes later as Liverpool won 2-1 in Tuesday's League Cup fourth round tie.
Marvin Emnes' 65th-minute strike had earlier been cancelled out by Mario Balotelli four minutes from time and while Monk was disappointed with his side conceding two late goals, it was Fernandez's dismissal that left him irate.
"The sending off clearly isn't a sending off at all," he told Sky Sports.
"Hopefully the referee will see some sense and the authorities will rescind that red card, because it wasn't a red card at all.
"It's an honest challenge. If anything, Coutinho's feet were higher than ours and actually went in over the top of our player.
"I don't quite see how the referee saw that, but hopefully he sees sense and rescinds it."
Monk had been pleased with Swansea's second-half display before things unravelled.
He added: "[In the] first half Liverpool were the better team, we allowed them too much space and too much control of the game.
"But at half-time we changed a few things, tweaked it, and were much more in the game second half. We played very well, I thought, got a deserved goal and really looked like we were going to hold on for the win.
"But a sloppy goal from our point of view, a few minutes to go, and conceding a goal from a cross like that, it was a little bit too easy. So we're very disappointed with that."
