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Walker is facing a two-match ban for simulation following the penalty he was awarded and converted against Celtic.
Visiting captain Scott Brown called Walker "a cheat" after Sunday's match at Tynecastle, with Celtic manager Brendan Rodgers saying referee John Beaton had admitted he made a mistake.
Hearts will make their case for Walker at a Scottish FA judicial panel hearing set for Thursday.
Walker, 23, is now free to play in Wednesday's League Cup visit to St Johnstone.
He scored from the spot to draw Hearts level in the first half before Celtic won the game with a late winner from Scott Sinclair.
Hearts head coach Robbie Neilson said on Tuesday morning that he was disappointed by Brown's "cheat" comment.
"I don't think you should be saying that about fellow professionals," Neilson told BBC Scotland.
"If you have got an opinion on anything you are better just keeping it to yourself."
Neilson did speak to Brown at full time but the penalty incident was not discussed.
"I spoke with Scott after the game but just about coaching as he is doing some coaching with the under 20s.
"What happens on the football park happens on the football park. We move on, he is a good guy and he speaks well and he is into his coaching so there are no issues there at all."
"Disciplinary Rule 201 - At the above match you committed an act of simulation in that you did pretend that you were fouled by a player on the opposing team, namely Kieran Tierney, and did thereafter dive in the penalty box of the opposing team. That this act of simulation caused a match official to make an incorrect decision, namely the incorrect awarding of a penalty to Heart of Midlothian FC."
Hearts are to contest a diving charge against winger Jamie Walker.