What would you do if another child kick your toddler intentionally?

I hope others will share their experience and advice.

Yesterday I brought J to the playground after the daycare. A boy about 4-5 years old (or definitely at the age where he is morally aware of right and wrong) blocked the bridge to the slide and kicked J on the stomach. It wasn't just a case of a child hitting another child, but a karate-style kick with full leg power 90 degree perpendicular swing including the thigh muscle. J fell backwards both due to the physical force as well as the shock that someone would kick him in the stomach and cried. I picked J up and carried him. The boy's mother was just few steps beside him and witnessed everything. At first, I gave his mom a sympathetic look, feeling sorry for her that she has such a violent child.

I then looked at the boy, and he had this "ya ya papaya" look on his face, meaning he gave the "I am invincible look". However, when his mom did not make any attempt to apologize nor to correct the boy, my sympathy turned into anger. I took the matter into my own hand, went over to the boy and said to him, "You should not kick another boy. You should apologize". At this point, his "ya ya papaya" face began to disappear. I have achieved the results I wanted, although I did not get him to apologize. His mom still did not say anything. She still did not ask him to apologize. She just took him and they got ready to leave the playground.

If J is at the age where he is speaking and has a command of language, I would have asked J to say that to the boy himself. However, J, 22 months, is not at that age yet and still can't speak in sentences. I felt that I have to stand up for my son.

Looking back at this incident, I wondered whether I had done the right thing in interferring in other parents' parenting. At that moment, I have forgotten that I am a Christian, and I just felt that I needed to tell the boy off. If his parents do not condone such behaviour, the boy could just go on and kick other children younger than him and get away with it.

What would you do if you were in my shoes? What would you have suggested that I do? What would Jesus do? What does God think that I should do? What would my pastor do? Help, I am struggling to find some Godly guidance. I would appreciate to hear some advice from others.

Apart from the physical blow, I was more worried about the emotional blow. I was worried that J's self-confidence would be affected. But I was relief that J seemed to have more self-confidence I thought. He cried and asked to be carried. Then J asked to eat and drink. I brought him to a table and gave him some biscuits and plain water. J stopped crying at the table and ate the biscuits and drank the water. Maybe that was J's way of telling the boy in his own toddler's body language, "I am going to eat and grow big and strong so that you will think twice if you want to issue that karate kick at me again!" All this while, the bully boy was just nearby the table, wearing his shoes and getting ready to leave with his mom from the playground. Still without any word, nor any apology from either the mother or son. J seemed very forgiving, facing the boy straight and did not turn away from the boy's face or hide into my embrace. Maybe I should learn from my son J to be as forgiving.