Iranian foreign policy has not been "revolutionary" but has focused on better integration with global community
In contrast, a major feature of the supposedly “revolutionary” Iranian regime's foreign policy has been to try to integrate Iran into as much of the existing international order as possible, notwithstanding its Western origins. (Iran, unlike China, does not have anywhere near the strength to erect alternatives to Western institutions even if it wanted to.) This strand of Iranian policy is reflected not only in what Iranian leaders say but also in what they do, such as participation in this week's Nuclear Nonproliferation Treaty review conference. The nuclear agreement currently being negotiated with the P5+1 is itself one of the clearest manifestations of the Iranian policy of making significant concessions and sacrifices in the interest of becoming a more integrated member of the international community.
The depiction of current-day Iran as “revolutionary” in the sense of upsetting the international apple cart requires as much ignoring of recent history and actual patterns of Iranian behavior as does the likening of current Iran to 16th century Safavid imperialism. In the early years of the Islamic Republic there was indeed a belief among many in Tehran that their own revolution might not survive without like-minded revolutions elsewhere in the neighborhood. But with the Islamic Republic having now survived for more than three decades, that perspective is obsolete.
A good case in point is Bahrain, given its Shia majority population and historical Iranian claims. Despite the unrest there in recent years, it has been a long time since any reliable reports of Iranian activity there that could honestly be described as subversive or revolutionary. In stark contrast to whatever minimal Iranian involvement there is in Bahrain, Saudi Arabia rolled its armed forces across the causeway to forcibly put down Shia unrest and prop up the Sunni regime in Manama. A similar contrast prevails today in Yemen, where any Iranian aid to the Houthis, whose rebellion was not instigated by Iran (and during which the Iranians reportedly have counseled restraint to the Houthis) is dwarfed by the Saudi airstrikes that have killed hundreds of civilians. (Tell us again—which Persian Gulf country is the hegemonic power?)
Stories of Iran as a supposedly threatening regional hegemon are not only not a reason to oppose reaching agreements with Tehran; the stories aren't even true.
Iran has a long history of supporting terrorist proxies and promoting an aggressive foreign policy that has caused instability in the region. However, we should be careful not to overstate the impact or threat from their regional ambitions as they have had limited success in spreading their revolutionary ideology. Additionally, recent instability in Iran's traditional spheres of influence (ex. ISIS and Syria), is forcing them to refocus their efforts and reduce funding for other activities.