Sevilla have been accused of stirring up the atmosphere ahead of Wednesday's first leg at the Sanchez Pizjuan, planning special security measures to ensure no Real officials are allowed near the referee at halftime.
"Mourinho doesn't want to get involved in what's being said and what's happening," Karanka told reporters at Real's training ground in Madrid.
"He doesn't want to be punished for trying to defend the club. He wants normality and has decided I appear instead. He doesn't want to add to what's coming from Sevilla. Whatever he says will be used to punish him."
Sevilla's unusual actions are a result of a controversial semi-final second leg between the two clubs in February 2004.
Real official Jorge Valdano, now the club's director general, was accused of speaking to the referee during the interval minutes after Zinedine Zidane was sent off.
Sevilla then had Javi Navarro shown a second yellow card early in the second half.
Sevilla have also made a television commercial to promote the tie in which their players strip to the waist, put on war paint and strike aggressive poses, over a slogan in Portuguese which says "We are going to leave you without a title."
Karanka added: "Sevilla have created a heated atmosphere for the game. The disciplinary committees will have to decide if it is punishable or not, like they have done with Mourinho.
"It's a semi-final and Sevilla have a good record in this competition, but we aren't going to war."
Mourinho has had a number of brushes with footballing authorities this season, and was investigated by the Spanish football federation after being accused of helping create a hostile atmosphere around their La Liga match away to Sporting Gijon back in November.
