Football's governing body has heavily criticised the Italian team for their attitude following their exit from the World Cup.
A spokesman for Fifa said that the behaviour of the Italian squad after their defeat by South Korea in a second-round match on Tuesday was not acceptable.
Italy were knocked out of the tournament by South Korea on Tuesday courtesy of a golden goal by Ahn Jung-Hwan.
Italy were angered by the standard of refereeing in the match, during which they had their fifth goal disallowed in their last three World Cup matches.
But Fifa spokesman Keith Cooper defended the standard of refereeing - and went on to fire a broadside at the Italians.
"I do know that cooperation with the Italian team after last night's match was - and I will be diplomatic and say it was extremely difficult," Cooper said.
"We understand that to a large degree. The disappointment of elimination is always huge. Some nationalities, some cultures can bear that more easily than others.
"Having said that, we do regard the professional as having a sense of obligation towards the media to enable you to do your work.
"We try to stress to the players that they are not actually talking to you, they are talking to your readers, listeners and viewers.
"And so by refusing to talk to the media, they are refusing to talk to the fans, which is very regrettable."
Cooper insisted that the overall standard of refereeing during the World Cup had been good.
"I have said on many occasions that referees are subject to making errors like coaches, players and journalists," he said.
"It is always going to happen. The inaccuracies have been kept to a minimum."
Trapattoni was incensed by decisions that saw Francesco Totti sent off in extra-time and a goal by Damiano Tommasi controversially ruled out for offside.
Italy had refereeing decisions go against them in their final two group games as well.
Trapattoni's men had two seemingly legitimate goals disallowed in their 2-1 loss to Croatia in the group stages.
Another two goals were ruled out in the following match against Mexico, leaving Trapattoni seething.
"It was obvious from the start which way the
wind was blowing," he said following Italy's exit.
"The World Cup started like this for us and kept on in the same direction.
"Inability and low attention in the end caused a disaster like this.
"You can't play a World Cup with incompetent
linesmen. I've never experienced such a negative moment in my career.
"We go out with our heads held high, but with a lot of recriminations. If we talk about who should have won, I'd say it should be Italy."
Italy striker Alessandro del Piero added: "There have been many mistakes, too many - it hurts a lot."
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