The Dutch wideman was dismissed after the final whistle had blown to signal Manchester City had beaten the Terriers 2-1.
Van la Parra pushed Leroy Sane during a heated exchange to incur a straight red card and a three-game ban, meaning he misses tomorrow’s trip to Arsenal.
“I had a serious conversation with him before training,” said Wagner. “It was an easy conversation because what I had to say was obvious.
“He totally understood and also apologised in front of the players for what he did. So, now, we leave this behind us. i do not want to make it bigger than it is.
“It happened, take a fine and accept it and then carry on.”
Elias Kachunga or Collin Quaner seem most likely to come into the starting XI, with Tom Ince switching from the right to left flanks.
Another option is to bring Chris Lowe in at left back and push Scott Malone further forward. What Wagner won’t do, however, is rush Kasey Palmer back after his three month absence with hamstring trouble.
The Chelsea loanee came through a third Under-23s game this morning successfully but he will not travel to the Emirates.
Wagner added: “Kasey is a possibility for the near future. Not tomorrow but the near future.
“We will have options for this position, Colin Quaner did the role very well and Kachunga should be fresh for tomorrow after not starting on Sunday.”