Premier League champions currently suffering their worst start to a top-flight campaign.
Moyes failed to adequately strengthen the squad he inherited from the retired Sir Alex Ferguson and he missed out on several summer targets, only managing to complete a deadline day swoop for Marouane Fellaini.
But the former Everton boss has told fans that he may not be able to sign the players he wants in January and that his current crop of players must start improving if they are to successfully defend their Premier League crown.
He told MailOnline: “I’ll look at January but I wouldn’t want people to have big expectations about what you would sign or do in January because I don’t think January has in the main been a really good month to sign really at the top.
“I’ve got really, really top end players, great players to work with. But undoubtedly we will in time try to make that better, that’s part of the job.
“The job is to progress, to make progress at Man United. We’ll look to add to the squad if the right players come available.”
Moyes’ comments are bound to rub salt in to the wounds of the United supporters who currently see their team languishing in 12th in the Premier League after losses to West Bromwich Albion, Liverpool and local rivals Manchester City in their opening six games of the campaign.