According to the Evening Standard, the Eagles want to recoup some of the £27m they paid to sign the Belgian striker from Liverpool in 2016.
The newspaper adds that Benteke, who was the subject of a bid from Chinese Super League side Beijing Guoan last year, could be tempted by further offers from China.
"Christian Benteke has been the toughest decision," Martinez said of the striker's omission. "But it is for the balance of the squad. We have two number nines and Michy Batshuayi and Romelu Lukaku have taken those positions."
Benteke's current Palace contract runs until 2020.