The Uruguayan has previously been linked with a move to North Africa as well as the Gulf region, having publicly revealed he was ready to leave Chloorkop.
Speaking on Metro FM’s Sports Night Amplified with host Andile Ncube, the Downs mentor appeared to question the player’s commitment.
"As the coach I have the unfortunate privilege to make decisions based on what I see every day at training and for me, there's just more to the game than the pass, the dribbles, the things and that's not just for Gaston, that's for all the players at Mamelodi Sundowns. It's the feeling of trust, it's the feeling of investment," Mokwena said.
Mokwena, the son of Julius Sono and nephew of Jomo Sono, used his family as an example to strengthen his point about loyalty.
"I come from a family that has invested so much in football and I understand for example that football is not just a game that is to be played without emotions, unfortunately, because I have a late grandfather that died because he was on his way to Welkom and wanted to recruit one of the best players for Orlando Pirates at the time and he passed away mysteriously on the side of the road for football,” the coach added.
“I have an uncle who went overseas and was given a jersey by the greatest, Pele, who left his own wedding to go and help his team win a final. Those are my expectations from my players."
Sirino has twice been pictured wearing an Al Ahly shirt when Sundowns faced the Egyptian giants despite being contracted to The Brazilians.
Given his family history, this still bothers Mokwena.
"That's the depth of investment I expect from my players and when I don't get that, when I don't get that sense it is very difficult for me to play you in this team. What also doesn't help is by nature as human beings, if you express publicly not once, not twice, not three times, you can't hold it against him unfortunately or fortunately because he is also very good person, he's someone I like a lot actually Gaston Sirino but it's difficult to get the best out of someone who doesn't want to be there."