Turkish league leaders Galatasary said the club planned to launch criminal proceedings against Jose Mourinho for "derogatory statements" against Turkish people.
The club said it would also submit complaints to governing bodies UEFA and FIFA after the Fenerbahce boss's comments following Monday's 0-0 draw between the top two sides.
The former Chelsea, Manchester United, Tottenham and Real Madrid manager made comments about the Galatasary bench "jumping like monkeys" after an early challenge and the match being better because it was not officiated by a Turkish referee.
Monday's game was refereed by Slovenian Slavko Vincic after both clubs requested a foreign official take charge.
A statement from Galatasary said Mourinho "has persistently issued derogatory statements directed towards the Turkish people" since taking over at Fenerbahce in June 2024.
"Today, his discourse has escalated beyond merely immoral comments into unequivocally inhumane rhetoric," the statement said.
"We hereby formally declare our intention to initiate criminal proceedings concerning the racist statements made by Jose Mourinho, and shall accordingly submit official complaints to UEFA and FIFA."
Describing Mourinho's conduct as "reprehensible", it said rivals Fenerbahce professed "to uphold 'exemplary moral values'."
The statement was posted on the club website under the headline: "Say no to racism."
Mourinho has previously been fined and suspended for his comments about Turkish match officials. And the Portuguese was again critical of Turkish referees in a press conference after the match.
"I went to the referees' dressing room after the game. Of course, the fourth official was there, a Turkish referee," Mourinho told the press conference.
"I told him (Vincic), 'Thank you to come here because you come for a big match and you are responsible for a big match.
"And I turned myself to the fourth official and I (said) 'this match, if you are the referee, this match would be a disaster.'
"And when I say him, I say the general tendency."
Mourinho also praised Vincic for not giving a yellow card to defender Yusuf Akcicek early in the match despite the animated reaction of the Galatsarary bench to a challenge.
"I have also to thank the referee because with a Turkish referee after the big dive in the first minute, their bench jumping like monkeys on the top of the kid, with a Turkish referee you would have a yellow card after one minute and after five minutes I would have to change him," he added.
Earlier this season, Mourinho was handed a one-match ban and been fined almost £15,000 for his response to Fenerbahce's 3-2 Super Lig victory at Trabzonspor.
The Portuguese was charged with "unsportsmanlike behaviour towards opposing team fans" and "diminishing the value of Turkish football and... discrediting the impartiality of the referees and other match officials" during an outspoken post-match interview.
