The Spanish goalkeeper was left in pain after colliding with his countryman in the second half of the 1-0 win against Nuno Espirito Santo's men.
De Gea revealed he will not be injured for United's next game against Aston Villa on New Year's Day but claimed he was shaken by the Traore incident while struggling on the Old Trafford pitch.
"Oof! I was lying on the pitch," said De Gea afterwards. "He's one of the strongest players in the Premier League, so it was very painful in my arm, in my stomach, but it was fine. We win the game, so everything's fine.
"I feel very well. It was just when I hit Traore it was painful, I can't breathe, but it was fine."
Asked about the growing belief in the dressing room of a first trophy since the 2017 Europa League, he added: "Of course, I think there's belief.
"You have to believe, keep believing all the time but at the same time we have to be calm because this is a long way to finish, many games to come.
"We have to be very focused on Aston Villa and then to the next game and then to the next game."