Diamond was dismissed after 76 minutes for a head-butt on Dons defender Pim Balkestein.
Rowett said: "I would be very surprised if Zander's head-butted him.
"He went down very theatrically if I'm honest and the referee, if he's seen any contact, has reacted to the way he went down.
"There was a lot of tussling in the box, people's arms around people, and I think Zander was trying to release himself, but I need to see it again.
"We will appeal it, there's absolutely no doubt about that."
Debut goals from Gary Alexander and Michael Symes ensured the points were shared at Kingsmeadow.
Rowett added: "Earlier in the season, even with 11 men, we've conceded two or three away from home. I think we defended really strongly here and it was a good performance in the end.
"That's two games away from home where we could easily lose our head, and maybe in the past we have, but we've come back and got a point which shows that the character of the team is fantastic.
"In the second half we hoped to get better balls into our strikers, and more possession, but the sending off killed that."
