Jacko confirmed through local media that Roberto Di Matteo's side had a big bid for N'Guessan turned down in the transfer window.
Having seen one bid turned down, the Dons followed up another offer which was also instantly rejected.
N'Guessan has scored four goals in his last five games and has already been linked with a move to Premier League trio Wigan, Hull and West Brom.
However Jacko decided to speak out in the wake of Lee Frecklingtons move to Peterborough.
"We turned two really good offers down for Dany N'Guessan from MK Dons so we're not a selling club," said Jackson.
"While we felt it was the right time for Lee to go, it was slightly different for Dany who is a key player for me.
"We decided to keep Dany N'Guessan and I'm glad we have done.
"When I first arrived he was a player who was up and down and very sulky, but this season he's probably been our most consistent player.
"I'm delighted that we turned the bids down and am hoping that Dany will extend his contract here."
The Imps are now expected to offer Dany a new contract in the coming weeks.