Wasn't the operation planned, to rescue hostages that the regime wasn't capable of protecting? In fact, didn't care to protect? Wikipedia seems to say so.
After all, you're supposed to police your own residents, and keep them from invading embassies, which are foreign turf. You're also supposed to respect that aspect of diplomacy. Letting your citizens raid an embassy and kidnap diplomats is the act of a banana republic, and definitely signals the end of diplomacy.
If the current regime is upset at someone trying to rescue their own people kidnapped from their embassy, then frankly that regime is insane. Iran is 100% at fault for allowing that to happen, not working quickly to resolve it. The US is 100% correct to have sent people in to rescue their own people, under those circumstances.
If the embassy was better armed, with more security, they'd be completely correct to shoot-to-kill every single person who stormed that embassy. Yet sending people in to rescue them after the fact is... wrong?
Hardly, and I sincerely doubt Iran is significantly upset still. Yelling about it, sure. Upset for real? No.
After all, it was a spectacular failure.