Enzo Maresca said Nicolas Jackson's costly red card against Newcastle needed to be avoided and that he would speak to the Chelsea striker.
Jackson was shown a straight red card for smashing his right forearm into the face of defender Sven Botman during the first-half with Chelsea trailing after Sandro Tonali's early goal.
Bruno Guimaraes struck a late second for the hosts, who struggled in the second half against 10 players but earned a crucial victory in the race for the Champions League.
"The red card has affected the game, no doubt," said Maresca. "In this stadium against this team it's already complicated and if you give them one extra player it's even more difficult. But overall I think, especially in the second half, we had three big chances. With 10 players it's not easy.
"In terms of the red card, I think if the referee decides for a red card, it's a red card. The only thing is in some different stadiums, sometimes it's more the noise that decides if it's foul or not.
"And then with Nico I didn't speak [to him], it's not the moment. Probably in the next day we're going to speak with Nico."
Asked whether he thought the home crowd had influenced the red card decision, Maresca said: "No, I don't think so. I don't think in that one. In the rest, my feeling from the touchline is that sometimes the noise decides if it's foul or not."
Maresca hoped Jackson, who will now miss Chelsea's final two matches against Manchester United and Nottingham Forest, would learn from the red-card incident.
"What you have to do is avoid this kind of thing because you need all your squad available for the next game," said Maresca. "But it happened, now he will be out for the rest of the season and hopefully he can learn for the future.
"The season for him is finished. He's our nine, he's our striker, the other one is Marc Guiu that you know is already injured from the last three months. He's close to being back and we need to find a different solution for the last two games. They are both important games."
