Vaughan believes that the issue could have been avoided if Pietersen's teammates had spoken to him.
Vaughan told BBC Sport: "I'm not too sure if that conversation took place. If it has and he still acted the way he has, he's been an idiot.
"You can see how he winds people up but he needs managing. Don't let him go to a media conference because you know he's likely to say something that's going to upset a few people."
The Surrey batsman was dropped from the England squad in a row over text messages sent to members of South Africa's Test team.
Vaughan was the England captain when Pietersen made his Test debut for England in 2005.