Shahter's Portuguese coach Paulo Fonseca laughed when they asked him about the decision.
"It's hard to talk about punishment after such a result, but it's funny, that's all I can say," he said.
"Everyone has seen him, but not because of the sanction we lost," he added.
City manager Pep Guardiola agreed that the referee erred in the wrong and said that the event highlighted the need to introduce a video-assistant referee (VAR) system.
"We were aware that this is not a punishment, but we do not want to be in this position," said Guardiola, who admitted that Sterling could then tell the judge.
"You know VAR and what is it – the judge needs to help because they do not want to make mistakes.
"The game is so fast, so fast these days. I should tell someone something for someone," he added.
The social media was illuminated by punishment.
The city had two additional complaints because Sterling and David Silva had come under the challenge, but Kassai had no other choice than to return to the city 18 minutes ahead of time.
Shakhtar had the right to feel hurt, but for the second time in two weeks they tested the City, who won with certain Sterling, Riyad Mahrez and two other hits of Jesus.
Silva obviously fell Taras Stepanenko and Jesus shot at the top corner.
The result at the Etihad Stadium ensures that the place in the charity heart goes to this weekend derby against Manchester United, decided to rest Sergio Aguero, Leroy Sane, Benjamin Mendy and Vincent Kompany.
Reuters, with agencies