Stoke managed to net a last-gasp equaliser at the Britannia and get a 1-1 draw.
Mancini told Sky Sports: “Yes, it is difficult because we deserved to win this game because we did not concede any chances for them to score.
“I think that we deserved to win, I’m disappointed for the guys because they played very well.”
He added: “The second half we played very well, we had always the ball, we conceded nothing.
“I think that we are very unlucky to have lost the goal.”