The Welsh club had hoped to lure the player to the New Stadium on a season-long loan, but Coleman wants him to play at a higher level.
The Cotagers boss said: "My heart says I want to be nice but I have to do what's right for Darren and Fulham.
"We don't want to let him go to a League One side. He needs to go to a Championship team on loan, and then come back to us a better player with more first-team experience" "
The Cotagers boss said: "My heart says I want to be nice but I have to do what's right for Darren and Fulham.
"We don't want to let him go to a League One side. He needs to go to a Championship team on loan, and then come back to us a better player with more first-team experience" "