Assombalonga has been linked with a move to Norwich City, with suggestions that he could be set to move on.
However, Forest have already rejected one offer from Norwich for their most dangerous front man - and are set to continue to turn down any further bids.
Norwich had seen Assombalonga as the ideal addition, as they chase an immediate return to the Premier League.
Forest, though, see Assombalonga having a key role for them - now he is back fit.
The former Peterborough United striker barely featured last term, after injuring his knee.
However, a goal against MK Dons towards the back end of the campaign showed what he could do - and Forest are set to build their attack around his talents.
Assombalonga scored 15 goals in his first 29 Championship appearances for the Reds during the 2014/15 campaign, before picking up the serious knee injury.