York's finance director Terry Doyle said: "As a board, we are very disappointed for Lee Bullock that Cardiff, as yet, have not took up their option to sign Lee Bullock. He has worked hard since moving their on loan and has been successful, showing that he's very capable of playing at that level.
"If Cardiff don't choose to sign Lee we are aware that other First Division clubs have already shown an interest."
Lennie Lawrence was said to be discussing Bullock with York manager Chris Brass on Friday.
Lennie has expressed his interest in signing the player, his loan spell has now ended and York will re register him as a York player if Cardiff do not complete the deal or risk losing him as a free transfer. Cardiff have agreed a fee for the player.