Based on my research, here is my fact-check analysis of this claim:

Reasoning:

• The claim that "The Iranian regime has confessed that the bombing occurred yesterday" is FALSE and has been debunked by multiple fact-checkers¹²³.
• According to PolitiFact, claims that the Iranian regime confessed that the Islamic Revolutionary Guard Corps bombed an Iranian school are rated "False"³.
• Iran's government has NOT taken responsibility for any school bombing. Instead, Iranian officials described the attack as perpetrated by U.S.-Israeli strikes¹³.
• Iranian Foreign Ministry spokesperson Esmaeil Baghaei stated: "The US & Israel launched an egregious, unwarranted act of aggression against Iran by indiscriminately targeting Iranian cities" and called the school strike "a blatant crime"¹.
• The "confession" claim originated from social media posts referencing a screenshot from a Telegram channel called "Radio Gilan"—but this channel is not an official Iranian state source; it supports the monarchy opposition².
• The screenshot claiming "The Islamic Revolutionary Guard Corps announced that this was an inadvertent mistake" was confirmed to be from an unofficial Telegram channel, not from official IRGC or Iranian government communications².

Overall validity: 0%

1. Did Iran 'confess' to strike on girls' school? Fact-checking claims ...
2. Investigation Debunks Claims IRGC Bombed Iranian School
3. Iran has not claimed responsibility for deadly strike on girls' school ...