Paris St Germain have told West Bromwich Albion they will have to buy Youssuf Mulumbu, if they want him.
Mulumbu had agreed to spend time on trial at The Hawthorns, and was ready to travel to England but PSG blocked the move and insist they will not let him train with the Premier League club.
The DR Congo international is out of contract at the end of the season and is considering his options, but PSG insist they will not let him train with Tony Mowbray's side.
"I do not want to put a block on Youssuf, or any player that wants to leave the club," Le Guen insisted.
"But I am against the idea of a trial during this period of the season.
"If West Bromwich Albion want Youssuf, they must make an offer - then we will think about it.
"I just don't agree that if we have a player under contract, who is then allowed to go on trial.
"I do not want players who are unhappy, but they must understand that they are under contract with their club."