Jackson has scored 38 times in 101 games for Gillingham following his move from Rushden and Diamonds in 2008.
Scally told the Kent Messenger: “He is worth money but it’s a question of what he is worth and we have had no credible offers so far. He’s a great lad and we would wish him well if he did ever leave.”
He added: “It’s a bit of a balancing act and that is where the skill of the board comes in. We have never stood in someone’s way who wants to move on and clearly he wants to play at a higher level, as will most of the team, and clearly he knows there is interest from some clubs.
“We just have to wait and see how the weeks progress.”