McCarthy claimed his players were upset because they felt Scharner had lifted his match shirt and displayed the contents of a T-shirt towards some of them during the latter stages of Sunday's Premier League match.
Wolves substitute Stephen Hunt appeared to be angered by Scharner's actions and was involved in an exchange with the Austrian.
But Scharner defended his actions, insisting the T-shirt only contained a club logo and the words 'West Bromwich Albion', and was aimed at the Baggies supporters.
McCarthy said: "Scharner had something on his T-shirt and showed it to the lads over the other side (of the pitch).
"There is no need for it and maybe that upset the lads. You can lose but you don't need your nose rubbing in it.
"If there were words said (between the players), it would have been because of that. He lifted up his shirt, there is no need for it.
"It's when you get responses. Take the mickey with the ball, that's the game. I get the hump with it."
But Scharner is adamant his actions were not meant to anger the Wolves players.
He said: "My kids gave me the T-shirt. They stuck a club logo on it and I was just showing it to the fans. That's all."
Wolves have now lost five games in a row as goals from skipper Chris Brunt and Peter Odemwingie secured Albion's first home win of the campaign.
McCarthy said: "I could say they were clinical as they had two good finishes and we didn't.
"We started well but being the best team for seven minutes is no good if you then concede. It could have been avoided.
"The second goal knocked the stuffing out of us. We had enough chances but we weren't clinical."
Odemwingie put a difficult week behind him, which had seen Nigeria fail to qualify for the African Nations Cup and further concerns over his ankle problem.
He came off the bench to score his second goal of the campaign.
Albion boss Roy Hodgson said: "It will give Peter a big lift. He was terrific when he came on.
"I was preparing for the game with Somen (Tchoyi) because I didn't think Peter was going to be fully fit and that turned out to be the right decision.
"He's a very good player and it's important for him to realise we are all behind him and it is not on his shoulders (to score all the goals).
"We have Shane Long now, Somen, Chris Brunt, good players to keep us going and provide the ammunition."
Albion moved out of the bottom three and Hodgson admitted: "It was a very important game and it was excellent to get our first home win of the season.
"It was also important to get our third clean sheet from eight games. That's more than the two for the whole of last season.
"If we keep three clean sheets every eight, we'll be fine."
Hodgson also believes McCarthy is under no pressure for his job despite Wolves sliding to 17th in the table.
He said: "I can't imagine for a minute that Wolves would want to sack Mick McCarthy, he's done a terrific job.
"If my team played as well as his today and lost, I think I'd be getting a pat on the back and people telling me to keep my head up."