"Not all the players are 100% happy with me at the moment, because I'm not extending everyone's contracts as we have done in the past," he said.
"It's something we will be looking at between now and the end of the season, there are a number of important players to the club who will need their contracts extending."
When asked about the club's financial clout in League One, Winkelman insisted the Dons had the ability to challenge in the league, but would remain cautious.
"We've certainly got enough to have big ambitions," he explained.
"But at the same time we want to run something that is sustainable.
I think if you want a type of football that's very route one... like certain teams we've played this year, then yes that's a way of playing
MK Dons boss Karl Robinson
"The club continues to make a loss every year, it's a seven-figure loss and we try to make it not multiple seven figures, which it has been in the past."
Meanwhile boss Karl Robinson was forced to defend his side's style of play.
He said he would persevere with the patient approach the Dons have adopted since he took charge in May last year.
"I think if you want a type of football that's very route one, very on the edge of your seat, where we go long and win second balls, like certain teams we've played this year, then yes that's a way of playing," he said.
"We want to play a type of football where we retain the football more than the opposition, it's the best home record this club's ever had and the reason for that is that we retain the ball longer than any other team in this league, that's a fact.
"We have more passes and a better completion rate than any other team in his league."
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