The summer signing from Anderlecht was booked in each of his first two games for the club, and was then sent off in the defeat by Arsenal in late August for a high tackle on Francis Coquelin.
But the Serbian forward says he is staying calm, and does not want to leave his side short again.
"As I showed against Chelsea, I can stay calm and I will keep working on that of course," he told Soccer Saturday. "I can stay calm in games and not get a red card again and not do something stupid so that I leave my team-mates playing with 10 against 11. For sure I will not try and do the same thing I did against Arsenal.
"Even when I play against my brother or my girlfriend, some games at home, I am always like this, nervous.
"I do not know, I am a winner and every game, even in training, I will try and win and do everything that I can do win the game."
Newcastle need all the help they can get against Manchester City at the Etihad on Saturday afternoon, with Steve McClaren's side sitting second from bottom with just three points from seven games.
McClaren has told Mitrovic he needs to keep a lid on his temper, and the 21-year-old knows he has to toe the line.
"After the game against Arsenal, players really tried a lot [to wind me up], especially defenders, but I tried to not answer them and stay calm and do my best to score.
"You do not need to do stupid things but to put your aggression towards scoring goals and to give everything to help your team-mates.
"I speak to the coach about this and especially as I have had the last two weeks free.
"He is really positive, I like him a lot, we have a good relationship, he helped me a lot, especially in the days when it was a really difficult time for me."