"He was playing dirty all day,'' Alexander said on Wednesday of Seattle's Breno Giacomini. "That's the type of player he is. I've just got to be smarter.''
Alexander was ejected in the first half of Sunday's 12-7 loss after throwing a wild punch at Giacomini, one of the most penalized players in the league last season. The NFL informed Alexander of the fine on Wednesday.
Alexander said he is considering appealing the fine because he wasn't the first one to throw a punch. Head coach Ron Rivera also said it was a matter of the second person getting caught.
"The play before that I feel he tried to take a shot at me,'' Alexander said. "Then the play when he had me, I heard the whistle blowing and he still tried to drag me to the ground. Before I knew it I reacted before thinking.
"It was one of those situations that just got out of hand, and the referee threw me out.''
Alexander, who has a base salary of $480,000 this season, said the fine hurts "when you need the money, man.''
The Panthers need Alexander on the field, particularly against the up-tempo Buffalo Bills this week where fatigue can be a problem and a four-man rotation is better than three.
"I can't let my team down, and that's what I felt like I did,'' Alexander said. "It's in the past and I'm trying to move forward from that and don't look back.''