Glazer is believed to be in the final throes of launching an £800m takeover bid for the club, but Dyke believes the deal would not be in the best interest of the club.
Dyke, also ex-director general of the BBC, says any such deal would "endanger the very existence of the club".
He added: "The only way he can afford it is by taking on a massive amount of debt. The risk is too great. Manchester United may become the next Leeds."