The Senegalese striker was sent off for making an offensive gesture towards the Seagulls fans after he scored from the penalty spot.
Leeds boss Brian McDermott told the club's official website: "I've spoken to El-Hadji Diouf and he has apologised regarding the sending off on Saturday.
"He has accepted the sending off and the club have fined him two weeks' wages which is the maximum we can do.
"I've had a good conversation with Dioufy regarding the future, he is fully committed for what is to come next season."
United have launched an appeal against the red card picked up by midfielder Rodolph Austin in the same match.