Fraser Forster's arrival from Celtic has seen Boruc lose his place in the team, and Koeman claims that he will not be considered for selection until the situation is resolved.
"I have spoken to him and said, 'I know you want to move.' That is normal," the Saints boss told members of the media. "Artur is training as before, but until deadline day he will not be involved in the team.
"After that we will see what the situation is. We will see what is best for Artur and best for the club.
"I want people who want to play for the club, and it is clear Artur feels he should be in the team."
Boruc, who moved to Southampton from Fiorentina in 2012, has one year remaining on his current deal.