Chelsea have sacked and since replaced the Italian with Liam Rosenior.
"There's no vision, they cannot see the future of it," Petit said on talkSPORT.
"It's only based on money, money, money. I understand that, that's the situation in football now. We have to accept it.
"But in the meantime, it doesn't mean you cannot have a vision on a couple of years and stick with it.
"It's the same situation at Manchester United. Amorim, it's kind of different in the way he reacted. But the way he said things about the board and the people in charge.
"It's funny, so many people have been asking me the same question for months and months, 'Why don't you become a manager?'
"What for? Explain to me? To get a headache every day when I go to the training ground with the players, with the press and especially with my boss?
"Before going onto the pitch and trying to win the games, I have to try and win the games outside the pitch. I don't have this energy.
"I love football, I don't want to be in trouble with people that don't get it, that don't understand what it means to win a game."