And Ferguson declared it was "time to move on" from a saga that has dragged on for almost a year since the Blues skipper was first accused of abusing QPR defender Anton Ferdinand.
Ferguson, who saw United full-back Patrice Evra and Liverpool striker Luis Suarez end their own racism feud in Sunday's game between the sides, said of Terry: "There is a danger of it resurrecting itself because it has been going on so long.
"But the fact he got a four-game ban, he may consider that is quite lenient considering Luis Suarez got eight.
"It is time to move on and so should the game."
On Friday, Terry was still awaiting the full written judgment of the independent Football Association panel over his guilty verdict, which also saw him fined £222,000.
The 31-year-old, who admitted saying "f***** black c***" during an altercation with Ferdinand but only to deny using the insult in the first place, had already been cleared in court of a similar offence and may lodge an appeal.
West Brom boss Steve Clarke, who was at coach at Chelsea for several years and helped nurture Terry, said: "I know John Terry. He is not a racist but he has been found guilty of making racist comments, which is probably slightly different.
"He was also found not guilty in a court of law. It's a really complex issue and, without seeing the full report, it is really difficult to comment on.
"Has he been a plonker? I wouldn't like to say that because that is you putting words in my mouth. John Terry is not a plonker.
"When I worked with John, I found him to be a really good guy. I couldn't see any sign of racism in him and I can only call it as I see it from my relationship with John Terry."
He added: "I think it's good there has been a decision. It has dragged on far too long.
"The one thing I would say about the whole episode is there were two high-profile episodes which happened last season and they are still dragging on and on.
"Hopefully now they are both resolved. I don't know whether John will appeal or not.
"I would like to think we can all move on quickly from it and, in a year's time, we are not talking about racism in the game, which will mean everyone has learnt a lesson."
Newcastle manager Alan Pardew called for the FA to make the penalties for racism even more "severe".
He said: "I am not party to all the information, but the games, the fine - you do want to see consistency in that area.
"That's something that I think needs to be looked at, and I hope the FA do that going forward because if it does happen again, it should be a severe fine if somebody is guilty."
Pardew said of Terry's punishment: "I think perhaps there needs to be some sort of explanation from the FA as to why - that would make sense."
He added: "You can't just wash it away or bury your head in the sand about it. You have got to deal with it.
"Show Racism the Red Card and those groups need to stay on their toes and make sure we eradicate it."
Fulham manager Martin Jol was pleased to see the FA taking action over racism.
"It happened a couple of times and I think in England you should make a decision on that sort of thing like Suarez and John Terry," he said.
"It was the end of it with the FA. They coped with it and this is what they should do."
Manchester City boss Roberto Mancini did not think racism was a problem limited to English football.
The Italian said: "I think this problem could also be all over the world not only here or in Italy or Spain.
"But I don't know this situation - I've just read about it in the newspaper."
Aston Villa boss Paul Lambert refused to be drawn, saying: "To be honest, I don't like to get involved with things like that.
"I don't know enough about it."