Reading made an approach for Ferguson last week as they continue their search for Steve Coppell's successor.
Ferguson was keen to talk to the Royals, but MacAnthony rejected the Championship side's request to speak to the former Manchester United midfielder.
"What I can't understand is a Championship club wanting to interview him rather than just offer him the job, that to me was a bit of an insult," MacAnthony told BBC Radio Cambridgeshire. "There is no get-out clause in his contract, if people want to come after our best assets they will have to pay a lot of money.
"Is there a figure for Darren? Like everything else, if it's right for the club and it suits us then of course there is a figure
"It's not a sign he wants to leave, there's no problem, we haven't fallen out, there's no aggro between myself and the gaffer. I think maybe we caught him at the wrong moment, it's an off-the-cuff remark, does he really want to go to Reading over us? I don't think so."