The Dutchman joined Seoul in March but has not appeared in recent games.
"Musampa still hasn't adapted to Korean football and he needs to become physically stronger," the former coach of Turkey said.
"From the first game he has shown his technical and passing skills and he just needs a little more time to adjust."
Reports in the Korean media suggested last week that the former Ajax, Atletico Madrid, Bordeaux and Manchester City star was ready to leave the club in July.
The player's management company dismissed the rumours.
"This is news to us and I deem it as an unsubstantiated rumour," Musampa's manager said in a statement made to Goal.com.
"Kiki is a FC Seoul player for at least two more seasons. He is there to help the team become champions and he has adjusted very well to Korean life thanks to his teammates and fans.
"He has been doing extra training of his own accord since he arrived in Seoul and with not a lot of time to adjust he is about to show what he can do."