Norwich City striker Jerome claims defender Bellusci made a racist remark during the first half of Tuesday's 1-1 Championship draw at Carrow Road.
Referee Mark Clattenburg stopped the game following an incident between the two players, then spoke to both managers on the touchline.
The Football Association confirmed on Wednesday that it is looking into the incident, and Cellino has backed his player.
"Bellusci is no racist," he told the Yorkshire Evening Post. "I spoke with him and he said 'you must be joking, I said nothing like this to him [Jerome].' He is surprised by this. He is shocked.
"I don't allow racists at this club and I won't allow racists at this club ever. If one of my players is a racist, I'll kick his a**e and kick him out before the FA has a chance.
"Bellusci says he spoke [to Jerome] in Italian. I don't know if he speaks Italian too but Bellusci swears to me he said nothing racist.
"He was p****d off, sure, because he got hit in the neck and the face but he denies anything racist. I believe him and and I'll support him.
"I'll write to them [the FA] to clarify my position on Bellusci and racism.
"If any Leeds player was shown to be a racist, he'd be out. That's my philosophy and my promise."
