The 24-year-old Dane says clubs in his homeland and Turkish side Trabzonspor have shown an interest, but that Reading do not want to let him go this season.
"It's really frustrating," Andersen told sporten.dk. "After long talks with the manager Brian McDermott and director of football Nick Hammond, they've decided to block any moves for me.
"So, you could say that I'm forced to put my own ambitions on hold to cater for Reading's needs.
"I've had offers from Denmark, which would have been nice as it would have given me a platform to show that I have what it takes. And I had an offer from Trabzonspor, which would have been interesting as they are a huge club playing in Europe."