There is two separate things:
(1) Claim you have correct Islam (Iran and Khamanei (h) don't do that, Khamanei (h) explicit says a lot in his speeches, that they can't claim they represent Islam and implemented it correctly, only that their spirit is Islamic (trying to submit to God)).
(2) Implementing your interpretation to the best of your ability.
Islam in Iran is not the real Islam, I agree. But we haven't seen real Islam since time of the Prophet (s). Ali's (a) government was turmoiled with war and justice he could never implement due to that. Imam Hassan (a) army was bought out by Mauwiya and had to settle for a treaty with Muawiya and give up government.
Our Imams (a) tried to get government back to God and them, but they failed to do so because of lack of support and betrayal.
However, anyone studying Quran and Sunnah, will see this is a struggle Prophets (a) in the past struggled for, and it's impossible that we are suppose to not want as much as Islam as we possible can implement to be implemented and instead have our opinions implemented. How would that work? We would have to put aside what we believe God taught and follow our own ignorance and conjecture with respect to judicial laws of government?
Iranian government is about doing the best with Islam we been passed down. Is it the real Islam? Definitely not in my view, but better then allowing porn, naked strip clubs, etc, etc... in society, better then legalizing prostitution, etc, etc,... the laws of Islam we won't get it alright till Mahdi (a) comes back, and we can always try to change people's mind about Islamic laws instead of saying believers should not rule or try to implement Islam with any interpretation.