Gcaba, whose contract with Pirates expires at the end of the season, is said to be seeking a move away from the club he joined in 2012 from Free State Stars.
Since the appointment of coach Milutin Sredojevic during the off-season, the 31-year-old defender has not played a single match for the Sea Robbers.
Struggling Durban side AmaZulu are one of the teams purported to be interested in the player as their defence has been unconvincing.
"I'm not aware of that," Mbele told KickOff.com.
"And you know me by now, I don't respond to rumours. Everybody that is there in the team is part of the squad and the technical team decides who is going to play in this particular match, and who is available and that is how the team goes.
"Going back to your earlier question, I'm not aware that he wants to leave."
Gcaba last played for Bucs against Golden Arrows in the final league match of 2016/17 when Kjell Jonevret's side lost 2-1 at Durban's Moses Mabhida Stadium.
The player's representative Mike Makaab, said: "It looks as if he might make a move in this window."