Atletico and Arsenal played out a 1-1 draw in the first-leg of their Champions League semifinal, with the visitors' complaints centred on Ebere Eze's late penalty claim being overturned by VAR.
Ref Danny Makkelie initially gave a spotkick, but VAR intervened and requested the Dutchman make a video check on the touchline. It was there that Makkelie was confronted by Simeone, who gave his version of the episode while waving his arms in aggressive fashion.
Eventually, Makkelie chose to reverse his initial decision - so angering Arsenal.
McManaman, in his pundit's role, stated: "I think the behavior of Diego Simeone and his assistants when the referee tried to approach the monitor was appalling.
"Once the whistle blows and there's contact, it's not a clear and obvious mistake. You shouldn't go back and re-referee it... Here we go again with VAR. I hate it, I hate it, I hate it. It ruins the game.
"I'm sure that if it had been in the opposing penalty area, Simeone would be frantically demanding a penalty. His behavior is absolutely deplorable."