No flag was thrown at the time in the game.
Both players told the Delaware County Daily Times that they would appeal.
"Yeah, that's crazy," Jackson told the newspaper.
Demps joined Jackson in the end zone after Jackson's 68-yard punt return gave the Eagles a 14-0 lead in the first quarter.
The two celebrated by turning toward each other, with arms folded and heads bobbing -- a violation of the league's rule against "prolonged, excessive, premeditated or choreographed celebrations, particularly after scoring plays."
Demps did not believe the two did anything excessive.
"Definitely I'm appealing," Demps said, according to the Daily Times. "I don't think it [warranted a fine]."
In addition, Eagles linebacker Tank Daniels was fined $5,000 for grabbing Redskins receiver Antwaan Randle El's facemask during a punt return. Daniels also plans to appeal.