Sunderland had the lead but Adam Johnson secured a late equaliser for City and made it 1-1.
Mancini said: “We started very slowly and we didn’t play very well in the first half, but in the second half we had six, seven, eight chances to score a goal.
“But this is football – if you don’t score you won’t win.”
He added: “I was not angry at half-time, just frustrated that we conceded a goal, but I was happy with the second-half performance and we had some very good chances.
“I am disappointed overall, but we have one game in hand and we must play Tottenham at home.
“If we want to reach fourth spot it is important that we win this game.”
