Mancini was due to hold an inquest with his players yesterday into the shock 2-1 defeat against second from bottom Wolves at Molineux.
He described it as "the worst game we have played" as Wolves hit back with goals from Nenad Milijas and David Edwards after Emmanuel Adebayor's penalty.
Mancini said: "We must find a solution because I am very disappointed. For me, we played really badly.
"To suffer two defeats in a week is unthinkable, sure.
"To go eight points behind Chelsea, that is frustrating – and I am very frustrated.
"We beat them (Chelsea) and just over one week ago we were only two points behind them.
"Last week we played fantastic football with 10 men against Arsenal for nearly 90 minutes. This time I am sorry for our supporters.
"We played very well for 15 minutes when we had four or five chances to score and then we played badly for the rest of the time."
Mancini added: "I don't know why we stopped playing but that is not good enough. I will speak to the players to find out why."
City striker Mario Balotelli showed glimpses of his potential after an injury-hit start to the campaign following his 24m move from Inter Milan.
But Mancini admits he is still coming to terms with the demands of the Premier League.
He said: "He must get to know the Premier League because it is different from Serie A.
"He did good things, he needs time but he is a good player."
Edwards's first goal for 14 months came at the expense of his former Shrewsbury team and housemate Joe Hart.
He said: "We are very good friends and, when I bought my first house, we were both at Shrewsbury together and he rented a room off me, for peanuts at the time.
"He owes me no rent and he has bought me a couple of drinks since then so it's okay.
"I said to him, I thought he did well, that he couldn't do anything about the two goals, but he was obviously disappointed about the result.
"But he was kind of happy in a way if anyone was going to score the winner, that it was me."
Wolves striker Kevin Doyle said: "We played well last week against Chelsea and decent the other night against Manchester United (in the Carling Cup).
"This time we got the result which makes a big difference.
"It is just little things, concentration and things like that, and we got it right. We played well, they huffed and puffed."