Giorgio Chiellini's goal was allowed to stand even though referee Ravshan Irmatov appeared to have blown for a penalty in Italy's favour seconds earlier.
Brazil angrily protested the goal, which made the score 3-2 to Brazil and brought Italy back into the match. The Uzbek official later confirmed he had whistled for a penalty, FIFA said.
"He admitted he made a mistake with regards to the incident penalty-goal," FIFA spokesman Pekka Odriozola said.
"(It was) a technical mistake, he has also admitted that, once you blow the whistle you have stopped play, you cannot give the advantage.
"He doesn't want to give make excuses, but he explained what the situation was like for him," said Odriozola.
"It was very quick, while he was blowing (for the penalty), out of the corner of his eye, he saw the goal could be scored, (then) the goal was scored. He was thinking quickly and he did not want to give any excuses."
Odriozola could not say whether the referee would be sent home from the tournament
"Without analysing the performances, (FIFA refereeing chief) Massimo Busacca said referees are humans and make mistakes just like anyone else, like players or strikers might miss a clear scoring chance," he added.