At our local village coffee morning several toddlers, including the children of my friends, were pushing chairs around noisily on the wooden floor making an awful noise. I had my toddler with me who was doing something else. I went over and took the chairs from the children saying, 'thank you for your help, I will put these away now' and I stacked the spare chairs.
One little girl burst into tears and so I said to her mother, who I do not know but see regularly, that i didn't mean to upset her but the noise was really awful in a friendly manner. The woman blanked me and said to her daughter 'I know you were only trying to help' as if I have been really unfair to her.
AIBU in thinking that sometimes children need to be told that something they are doing is unacceptable or was IBU to have spoken like this to other people's children.