Mancini felt his team gave their best but paid the price for failing to convert chances, a problem he feels is growing.
Mancini said: "The big problem is that to win games you need to score.
"If not, you lose or the game finishes 0-0. At the moment we are not scoring a lot of goals, as we did last year.
"When we get chances we need to score - we need to resolve this problem if we are going to win."