Iran did not admit to this. Further, the current suspicion that the killing of these children was done by the US is coming from a US investigation, not from some external source.
I do remember seeing a comment in a previous thread about this war. Some person (their profile said cofounder of docker or something???) and they posted a twitter link saying that it looked Iranian-caused. I don’t know what compels someone to take a twitter blue check as an authoritative source. But there were people peddling bizarre rumors without any real evidence