I think I would have reacted similar to you. I definitely would have been right there, ready to defend him. Although instead of looking for the parent, I may have straightaway told the child to leave mine alone. Parents not being present and paying attention is the problem!
I had something similar happen in our own neighborhood the other day. This 9 year old boy down the street broke a toy that my 4 year old was playing with. I didn't hesitate to tell him that if he didn't take better care of my boys' things, he could go home. I've never seen his mom and she's never outside while he's out playing. She may not even know how he treats other kids and their belongings.
I agree 100 % my only down fall was not being able to actually speak with the child due to a language barrier. Needless to say it makes for uncomfortable times for me and the only thing I can do is try. Thank you for your comment.