The Scotland international has made just three appearances for the Championship club this season but remains in his manager's plans and is unlikely to be sold in the January transfer window.
"Craig has put in a transfer request which we have refused," Mackay told the South Wales Echo.
"I don't expect any of my older players to be happy not playing but Craig is a member of my squad and part of my plans. He will not be leaving in January unless something drastic happens."
The 27-year-old has made just one league appearance this season having played 39 times for Mackay last term following his arrival from Dundee United.