Miroslav Klose earned the Biancocelesti all three points on Monday but the Inter coach was left fuming after Rolando was denied a penalty
Miroslav Klose struck the only goal of the game in Edy Reja's first match back in charge of the capital club as they closed to within eight points of the Nerazzurri in the Serie A table.
Mazzarri was angered that Andre Dias escaped both a penalty and a red card for a challenge on Rolando as his side began 2014 with defeat.
"The defeat comes after a tough game. Lazio remained compact, the pitch wasn't perfect - it wasn't easy, but it was a balanced game," Mazzarri told reporters after the match.
"Matches so well-balanced can also be decided on the right or wrong decisions of the officials. There was a clear penalty and a red card for a foul on Rolando from Dias. I don't attack referees for mistakes but, if you ask me, they committed two errors today.
"They were only good on the ball in the second half and won thanks to a great player like Klose."
Inter sit sixth in Serie A with 18 games gone - 18 points adrift of Juventus at the summit but six points ahead of seventh-placed Torino.