Shareef O'Neal just unleashed on a troll for blaming him for Bronny James' cardiac arrest ... calling out the distasteful comment in a fiery interaction on social media.
It all went down shortly after TMZ Sports broke the news of Bronny's medical emergency on Tuesday ... with one user referencing Shareef's own heart issues in an awful attempt to poke fun at the situation.
"Bronny started hanging with Shareef and now look," the tweet read. "@SSJreef stay yo ass away from him he’s destined for greatness not overseas 😆"
Shaq's son -- who had open-heart surgery to correct a right anomalous coronary artery in October 2018 -- got wind of the jab ... and he clapped back with a passionate response.
"That is very disrespectful of you to say," Shareef said in a since-deleted tweet. "I’ve been around Bronny for a very long time before this happened ... I’ll pray for you. You need help ... sick that you would even say something like that 🤦🏾♂️🤦🏾♂️🤦🏾♂️#dummy."
Shareef -- who's great friends with Bronny and was recently spotted with the USC hooper out in L.A. earlier this month -- added he doesn't like to acknowledge negativity on social media ... but this was something he couldn't let go without a reply.