City will have a heavy fine, a reduced Champions League squad and a limit on transfer spending for next season, while Paris St Germain have been given the same sanctions.
Platini told Sky Sports News: "The people at Manchester City are not happy, the people of PSG, they are not happy, but I think Manchester United, Everton, they are happy
It's very subjective
We have to follow the regulations but I think it's an historical moment and a good moment for football.
"My wish is not to kill the clubs
We have fair play to help the clubs have better governance
I'm not the person who decides..
but I think it would be a big mistake if we banned the clubs because financial fair play is to help them - not to kill them."
Meanwhile, Platini said he was still considering whether to run for the FIFA presidency but that he expects Sepp Blatter to stand for another term.
He added: "After the World Cup, it will be enough to think about that
I have all the World Cup, all the holidays, to think where I want to stay in the future.
"It's not clear in my mind
My problem is where I want to go
Where I want to be
If I want to be in FIFA, I will run for FIFA
If I want to be in UEFA, I want to be in UEFA
But I am very, very, very, very happy in UEFA."
Platini and Blatter have been exchanging jibes over recent months but the UEFA president insisted their personal relationship still remained good.
He said: "I have no problem with the man
I respect him
I have known him a long time.
"I supported him when he became president in 1998
But we have different matters
Football in Europe is not the football in the world
When he take a decision for the whole world, sometimes it's not good for the European football
We fight on ideas
Where is the problem? We have to fight on ideas."
Source : PA