The Spain international stood on the ankles of Emre Can and Martin Skrtel during the Premier League leaders' 1-0 victory at Stamford Bridge on Tuesday - which ensured they progressed to the final 2-1 on aggregate.
Sky Sports pundit Jamie Redknapp said Costa should have been shown a red card for the incident involving Can and Liverpool boss Brendan Rodgers felt the former Atletico Madrid man was "very fortunate" not to be dismissed.
He said: "I don't know what you understand by a stamp.
"Maybe you are already influenced by the campaign on the television with certain pundits saying that Costa has crimes - they must be nuts, the guy who says that.
"Sky call it a crime. I have to say that he goes for the ball, he chases it, the opponent [Can] goes to the floor and he puts his foot there when he is looking at the ball... What you call stamps, and Sky calls crimes, I have to say accidental."
