Lawrence was docked $21,056 for a roughing the passer penalty he received Sunday.
Keenum got hit high by a Cowboys defender on a second quarter incompletion while Lawrence caught the quarterback low.
Washington did not take advantage of the 15-yard penalty, with the Cowboys forcing a punt on the possession.
Lawrence had only one quarterback hit in the game. He has two tackles, a half sack, a forced fumble and a fumble recovery this season.