The United right-back was sent off during yesterday's 1-0 defeat at Old Trafford for kicking out at Luiz, who was caught by cameras smiling after he fell to the ground.
Ferguson, who has insisted that Rafael was provoked by Luiz elbowing him twice, believes that the Chelsea player's reaction was poor.
"He was smiling," the Daily Mail quotes Ferguson as saying. "It's bad. What kind of professional is that?"
Following the result, Chelsea moved back up into third place in the table.