The 22-year-old believes there is no place in football for Popov's actions but understands mistakes can be made in the heat of the moment.
"There’s no place in football for that," he told the Daily Mail.
"You can’t do it. The referee took the right action - it was a red card. But I think it was just a heat of the moment for him. He has apologised to me. I’ll take it on the chin… Maybe not on the chin! But I take his apology."
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He continued: "That third position is what everyone wants really. It’s a safety net for the Champions League.
"I think you do have to look into it a bit more. If an English club goes and wins the Champions League and they are not in the top four, all of a sudden they are in the top four."
Spurs' north London rivals Arsenal sit sixth in the league and are currently still involved in the Champions League but Walker can't bare to imagine suffering the same fate again.
"Please don't!", he added. "I don't think my Twitter account would hear the end of it."