Mihajlovic was sent off for two bookable offences and was later handed an eight-match European ban after television footage showed him spitting at Chelsea striker Adrian Mutu. Lazio lost the game in Rome 4-0.
"I would like to take this opportunity to apologise to my team mates, to the coach (Roberto Mancini) and to the club for my sending-off against Chelsea," Mihajlovic said in a statement on Lazio's official website on Tuesday.
He stopped short, however, of saying sorry to Mutu, who he accused of trying to provoke a reaction.
"I would like to stress that if I behaved badly, it was because I had been provoked in a fairly low way," he said.
"I'm sorry that the TV replay condemned only me, when there were also images that showed what I had to put up with."