Keane had taken aim at Matic over his comments whilst the Serbian midfielder was at Manchester United.
The 34-year-old, now at AS Roma, said both Chelsea and Man United were 'in his heart' following his spells at both clubs.
His comments didn't go down well with Keane, who questioned his old team's 'standards'.
The Irishman exclaimed: "Where's the standards at the club?
"Matic's talking about I'm leaving, I've had a great time, Man United will always be in my heart, oh and Chelsea as well, oh and Benfica don't forget them, they all can't be in your heart."
Matic has now responded to Keane's criticism, accusing the former Man United captain of not 'understanding that football has changed'.
He told the Times: "I have respect for what he has done but he needs to understand that football has changed.
"If I played for Chelsea, I cannot say I hate them. I cannot be angry when I'm talking to the press after the game."
The Roma man then touched on Keane's behaviour on the pitch, claiming his aggressive style of player would be prone to red cards in the Premier League today.
"The way he behaved on pitch, 70 per cent of it is a red card today," Matic added. "You cannot throw a punch when all the cameras in the world are there.
"The real hero is when you go out on the street and say something, but he was always very nice with me, so what he says in public, to be honest, I don't really care.
"I know what I've done in my career and I'm very happy."
Featured Image Credit: Alamy/YouTube
- Every word from Roy Keane's notorious MUTV rant, 17 years on
- Roy Keane Scolds Nemanja Matic For Post-Match Interview After Manchester United 1-1 Chelsea
- It’s been claimed that Roy Keane changes his personality when away from the cameras
- Nemanja Matic Does His Best Jose Mourinho Impression As He Responds To Taunts From Arsenal Fans