After a disciplinary hearing Tevez was fined four weeks' wages for committing five breaches of contract but it was reduced on Thursday when City accepted a ruling by the players' union, the Professional Footballers' Association (PFA).
The PFA backed the Argentine player's assertion that he did not refuse to come on as a substitute in last month's Champions League match at Bayern Munich but simply refused to again warm up and as such there was no justification for a fine other than the two-week maximum.
"I think it is a bit strange of course but the rules and regulations are there," Ferguson, who has praised City boss Roberto Mancini's handling of United's former player, told a news conference.
"It is a fact that the maximum fine you can give a player is two weeks' [wages]. It seems a bit crazy in that particular situation but it's there and there's nothing you can do about it."
City, who have expressed concern by an apparent conflict of interest between PFA Chief Executive Gordon Taylor and the disciplinary process, have avoided speaking about Tevez and the matter was once again off limits at a Friday news conference.
"It is not my problem," Mancini said when asked about the PFA ruling. "It is not important two weeks [or] four weeks."
The Italian, whose side built a five-point lead at the top of the Premier League with a 6-1 thumping of neighbours United at Old Trafford last weekend, was asked how the team had managed to avoid being distracted by off-field events.
"We are in the best moment in our history, our focus is only on the game, on training, the other situation is not important," he said.
Asked whether it had made his job more difficult, he replied: "I don't think of the other situation, I think of my job always, I try to do the best in my job every day."
Tevez is not the only City player facing disciplinary action at the moment, with defender Kolo Toure due to appear before a panel after serving a six-month ban for failing a drugs test.
"Kolo is a different situation, it was a mistake," Mancini said of the Ivorian, whose positive test came after he took a diet pill that was not intended to enhance his performance.
"It was a totally different situation, in the other case [relating to Tevez], I think every player should have good behaviour always, for him and for the fans."
While Toure is available to play, the future for Tevez is much less clear.
Mancini had said the striker was "finished" after the incident in Munich last month, while later seeming to soften his stance by saying he did not know if he would play for the club again.
Tevez, who said he was asked to warm up rather than play which he declined as he felt he had already done so enough, had previously made it clear he was unhappy in Manchester and local media have reported he will be sold in January.
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