The Nerazzurri threw away a 2-0 half-time lead and had to settle for a 2-2 result at Serie A strugglers Livorno on Monday night.
"Those who saw the match realise that it's one of those years," Mazzarri said to www.inter.it. "We just need look at it in a certain way.
"We need to take the positives from the game.
"My players showed a lot of character until, perhaps unconsciously, they thought that the game was over.
"Livorno were given a new lease of life after their first goal.
"We should have put the game to bed at 2-0 and we missed two or three big chances at 2-1.
"We got to the edge of the box and it was like we were playing PlayStation, we were trying to be too cute."
Mazzarri came out in defence of Inter midfielder Fredy Guarin, whose careless back-pass towards his own goalkeeper turned into a perfect assist for Innocent Emeghara to score Livorno's equaliser five minutes from time.
"In football, you are punished for your mistakes," Mazzarri said. "Guarin just needs to play like he knows how, mistakes like the one he made can happen.
"It's like when the ball goes through the keeper's legs, he didn't do it on purpose.
"Now we need to help Guarin, these things happen."
The outcome in Leghorn followed Inter's goalless draw against Udinese and left the Nerazzurri in fifth place, 15 points adrift of Napoli, who hold the last Champions League qualifying spot with seven games remaining.
Inter, who hold the last Europa League qualifying place, host Bologna on Saturday.