Mourinho was angry at referee Anthony Taylor for not awarding a penalty during the 1-1 draw at Southampton.
Midfielder Cesc Fabregas was booked for diving after going down in the area under Matt Targett’s challenge.
After the game Mourinho said: “The media, commentators, other managers are all doing it [putting pressure on referees].”
In his news conference later, he added: “There is a campaign against Chelsea. I don’t know why there is this campaign and I do not care.
“Everybody knows it was a penalty. The referee made a mistake, people make mistakes and he made a big mistake. He is a good referee and a good guy, he is young, he has years and years of football ahead of him but it is a big mistake.”
Referee Taylor deemed Fabregas to have taken a dive under pressure from Targett, but there appeared to be contact from the 19-year-old full-back.
Fabregas, who protested against the decision, said: “There was definitely contact, the referee didn’t have the best game of his life and I don’t think he will sleep that well tonight, he had an awful game.”
His manager Mourinho said recent pressure from managers on referees in the media led to the Blues not being awarded a penalty shortly after the break at St Mary’s Stadium.
West Ham manager Sam Allardyce accused Branislav Ivanovic of going down “looking for a penalty” in the Blues’ 2-0 victory on Friday.
And Mourinho said: “After the game against West Ham, Sam is speaking about Branislav Ivanovic [diving], what is this? Then, you come here [Southampton] and you have a crucial decision and the referee makes the wrong decision. He made a mistake. He assumed it.
“Out of nothing, Allardyce starts speaking about Chelsea players diving, then another coach and another coach. The referee changes a penalty for a yellow card.
“[The] same happened with Diego Costa in the game against Burnley. That I can’t understand. The reality is there are penalties and penalties – this one was a huge one. Match after match coaches are telling Chelsea players are diving. I will go to the referee and wish him a good year and tell him he will be ashamed.”