Bruce has revealed his reasons to the Birmingham Mail: "His agent left a message and said that he [Ghaly] wasn't happy with the standard of players here.
"I couldn't believe what I was hearing - and I've kept the message on my voicemail.
"When he had his one-to-one session with Dan, he was moaning we 'don't do this, don't do that' at Tottenham, it 'wasn't right' and 'ridiculous'.
"He had a right petted lip on.
"Yes, strong words were said and he was told in no uncertain terms that if he didn't like it, he should clear off."
Bruce continued: "There's no way I'm going to have someone criticising the squad, especially when they are supposed to be their new team-mates.
"And I'm not having anyone upsetting the togetherness and spirit we have worked so hard to build up here.
"I've had this before with a former captain [Kenny Cunningham] complaining about all sorts and I'm not going to keep fighting things like that. Yes, we train our players hard and we expect them to put the work in.
"What we do here was good enough for a World Cup winner [Christophe Dugarry] and so was our club and players.
"He had had the summer off and after reporting back hadn't trained properly for a couple of weeks or so as the transfer negotiations got going. For the previous four or five days he'd done nothing. He was way, way behind in his fitness."
Speaking after Birmingham's 2-0 friendly win over Sheffield Wednesday, Bruce labelled Ghaly a "prima donna."
"I only want people who want to play for Birmingham and wear the shirt with a bit of pride. If anybody's got any doubts - and he was doubting certain players' ability - it's not for me," Bruce said.
"I think the best thing is that we all draw a line under it. It was a sorry episode but I want people who are 100% committed and who want to play the game in the right way and not a prima donna who goes on the way he did.
"I didn't want him anywhere near my team.
"I'm not going to go into specifics, but he was criticising everything, including his team-mates, and that for me, is not on.
"I think he's a good player but you need somebody who comes through the door who is going to enhance the dressing room, not disrupt it, and I found his attitude and his arrogance insulting to the rest of the people who I employ, and more importantly the players."