Kovac admits Javi Martinez feigned cramp to "waste time" during the round 16 first-leg.
Kovac claimed the Spain midfielder's dramatic "bit of acting" was all part of the game - and helped the Bundesliga champions keep "calm" as the Reds pressed for a winner.
He told Sky Deutschland: “We all know the drill. It's close to the final whistle and you try to waste a bit of time.
“Javi has good performance data, meaning he couldn't have even had a cramp. That's all a bit of acting.
“Recently in Berlin, Kingsley Coman also pretended to have a cramp but he didn't.
“We have to bring calmness in the game. They do it well, they have the experience for that."