The teenager, whose York deal expires at the end of the season, is believed to be attracting a host of interest from higher division clubs.
Despite the League Two club being under pressure to sell, McNamara has said that Norwich's offer for Godfrey was nowhere near his valuation.
"Norwich made a bid that the chairman has rejected and I explained that to Ben because I believe in being open and honest," McNamara told The York Press.
"We're not working against him and the last thing the club would ever want to do is stand in the way of any player's progress, but the offer wasn't enough for the club or chairman to even think about."
Godfrey, who represented Middlesbrough at youth level, has made 14 appearances in all competitions for his current club this season.