Telling a child off

[confusedinlondon]

DS was at the park, riding his new bike. He had a heavy fall and shouted for me.
In the park there was another child (Y) who is abit of a smart arse and he began to laugh and shout at my son.
Y is in the park most days and has made fun of my DS previously, including pushing my daughter.
I told Y that he didn't need to laugh or make any comment about my son. On reflection I feel guilty about saying this to Y as they are both kids 8 or 9 and its all part of growing up.
Am I being unreasonable tell him off

Absolutely not unreasonable at all. The child shouldn’t be laughing at others’ misfortune! Hopefully you’ve made them reflect a little and they’ll have a more empathy in future.

yanbu. This kid sounds a little shit

YANBU - it doesn't sound like you were rude or inappropriate but just told him it's not nice to make fun of people (which by 8/9 he should already know!)

If he is prepared to bully other kids, he should be prepared for their parents to say something