The Uruguay international accepted the punishment on Friday, imposed for biting Chelsea defender Branislav Ivanovic on Sunday, meaning he will not play again for the Reds this season.
The Scot has compared the incident to the ban Eric Cantona received after the Frenchman was suspended for nine months in 1995 for kicking a Crystal Palace supporter and says he sympathises with the Reds.
| PREMIER LEAGUE LATEST
|22/5||Liverpool are 22/5 to be trailing at half-time and full-time v Newcastle
"I would never have listened to them in the first place saying that if 'you make your punishment we'll be happy'. We did that, gave him a four-month ban and then they turned round two or three days [later, and said]: 'Right, we're charging him.' We would never allow that to happen again at this club."
Sir Alex says Liverpool will feel vindicated they did not impose a ban on Suarez themselves as he feels it backfired on United when they punished Cantona.
"I'll bet they're glad they didn't [ban Suarez]. It didn't work with us, that's for sure," he added. "David Davies [then the FA's spokesman] promised us that, if we did it, there'd be no more action taken – bloody hell.
"If you think about it – a nine-month ban, it's quite incredible, I still can't get round that."