One newspaper has claimed Jermain has even bought a house in the Manchester area, but Glenn insists: "I have seen the speculation myself and it is always disappointing when this is started in the media - all I would say is that I would not encourage it.
"I see Jermain Defoe as a very important member of the team this year.
"I believe that him, David Connolly, and the striker that we will bring in hopefully over the next few days will have many, many goals in them to help us gain promotion.
"So I need to say very quickly to try and squash this speculation that I would not encourage a move from Manchester United - or any other club."
With Fredi Kanoute looking to tie up a move to Spurs, and Matthew Etherington coming the other way, Glenn's priority is to add to his forward line rather than reduce it further.
Although Jermain did hand in a transfer request at the end of last season, this was swiftly rejected.
Jermain himself has said he just wants to concentrate on his football, and his attitude in pre-season training has been praised by Glenn.