De Jong was heavily condemned his tackle on Ben Arfa at Eastlands in October. Ahead of the Boxing Day rematch with the Magpies at St James' Park, Mancini maintains De Jong was innocent of any crime and remains a key figure in his side's quest for silverware.
"I am sorry for what happened with Ben Arfa but this can happen in a football match," said the City boss.
"It has not affected Nigel and I never thought about leaving him out.
"There are a lot of players in the world who attack the ball like Nigel. In this instance he was very unlucky.
"But he is a fantastic player and very important for us.
"He is the only player we have got with his characteristics. He always stays in front of the defence, so he helps the defenders. But he helps the strikers and wingers too."
Mancini could do with instilling some of De Jong's battling qualities into Mario Balotelli, the £24million man who this week picked up the coveted 'Golden Boy' award as best young player in the world before producing a tepid display against Everton on Monday.
"Mario is a special player because he has a good attitude to play football," said the City chief.
"But you must also put your heart and your strength on the pitch. I know a lot of players, good players like Mario, who did not play football in a top team because of this. Mario has to prove he has the character."