The measures agreed on Thursday mean English top flight clubs could be docked points if they fail to comply with limits on financial losses and curbs on increases in player wages.
"It's all good in theory but the application of it will always be difficult. If people have money to burn they can place it anywhere in the world," Ferguson told a news conference.
"I'll be interested to see how they think they can operate it. It would be good if it was applicable but I have got my doubts. I think it's always going to be problem to try to enforce it."
The Premier League's rules are less stringent than UEFA's Financial Fair Play rules which will force top clubs from all leagues across Europe to move towards breakeven or face exclusion from continental competition.
The English measures aim to help ensure a five billion pound ($7.85 billion) television windfall leads to financial stability rather than being poured into lavish player wages.
Clubs will be limited to maximum aggregate losses of 105 million pounds over the three years from 2013 to 2016, coinciding with the new television contracts.
This should spell the end of a mega-rich owner pumping in hundreds of millions of pounds to buy instant success.
Arsenal manager Arsene Wenger welcomed restrictions on spending but said clubs should also be allowed freedom.
"I personally am for financial fair play in the way that companies and the clubs respect to manage the club with their own resources," the Frenchman told a news conference.
"For the rest, I am for freedom, how you use your resources inside the club. I am not in favour of a Brussels-type of society controlled from centralised, complicated rules. I believe every company should live within its own resources.
"For the rest, leave it to the company to manage their company how they want to do it."
Chelsea manager Rafael Benitez backed the regulations, perhaps surprisingly given his club, like Premier League champions Manchester City, has won trophies after a massive cash injection from a billionaire owner.
"If UEFA is doing the same, I think it's good," he said. "At the end of the day, you do things in the right way, it will be positive. Stability of the clubs is a key issue.
"The experience in Spain, for example, now with loans and they go to administration and it's a big mess. If you can avoid these things then I think it's much better."
Everton manager David Moyes, who knows all about strict budgets after more than a decade creating a competitive team on modest means, hoped the rules would not be a step backwards.
"We have to have competition. We have to make sure we give everyone the chance to compete," he told a news conference.
"I think we have to be careful that we don't stop people coming into the game who could help to push the game forward.
"I want to be given every opportunity to try to get to the top of the league with Everton. I hope this won't stop me doing that." ($1 = 0.6368 British pounds)
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