The choice of the "spread the revolution" calls by Khomeini as the igniting spark is subjective and ultimately arbitrary. In any case, the Ayatollah was referring to the need of overthrowing military or royal tyrannies and of installing popular institutions, designed to represent the will of the people. Diplomatically, it was not a very wise strategy, but, from a moral perspective, I fail to see why his speeches are so harshly criticised. Anyway, Iran has even verbally abandoned her promise to spread the revolution and has been harmoniously with secular states for several decades (including Syria, during the war with Saddam's Iraq). The report of the International Amnesty is as relevant to our debate about the present situation as the 1954 Guatemalan coup d'état.
I don't think that Iran, a country where transparent presidential and legislative elections are regularly held, qualifies as an authoritarian regime (defensive or limited democracy would be a more accurate description), nor do I believe that inventing a foreign enemy is a tactic exclusively reserved for despots. For instance, even today many well-educated American and European citizens are genuinely obsessed with the alleged threat infinitely weaker countries like Iran or Russia pose to their freedom or interests. Moreover, your interpretation is not supported by facts. Iranian-American relations normalised after the common campaign against ISIL began and deteriorated before the eventual disintegration of the Caliphate. The rapprochement is clearly linked to the nuclear deal, which was abandoned by the obviously unreliable Donald administration. The popular unrest in Iran is the direct consequence of the worsening state of the economy, which was itself caused by the negative impact of the recently
imposed sanctions.
The government, actually headed by the reformists, is blamed, rightly or wrongly, for economic stagnation and corruption, not for its ideological principles or foreign policy. Actually, as a result of the unprovoked American aggression against the Iranian Republic, according to a
statistical analysis of the effects of the "Maximum Pressure" doctrine upon ordinary Iranians, anti-Americanism is on record-high levels, while compromise was rejected by the majority. Several figures strongly tied with the clerical establishment, like former president Mahmoud Ahmadinejad, were positively viewed, while general Qasem Soleimani was the most popular public figure, even before his illegal assassination in Iraq. Meanwhile, 60% approve of the Iranian military presence in Syria, following the official invitation of Damascus and the actions of the Revolutionary Guards are deemed by an outstanding majority (80%) as vital for protecting the fragile security of Iran. I'd argue that their conclusions are justified, given the uninterrupted hostility of Washington against the interests of the Iranian people, as well as its long history of murdering Iranian citizens, many of whom being civilians, without any serious repercussions.