Omid Memarian reports on the question:
“Iran can be helpful in resolving the Syrian crisis and bringing the civil war to an end,” Hooman Majd, an Iranian-American journalist and the author of Ayatollahs’ Democracy, told The Daily Beast in an email. “As long as the US goal is not regime change, almost as a precondition, I think the Iranians and the Russians probably see it in their interests to bring the civil war to an end, and help manage the transition to a representative government, as long as that government has no elements openly hostile to Iran, to Shias, or to Russia (such as Al-Qaeda affiliated or sympathetic groups).”
“Iran has shown a willingness, (particularly the new administration in Iran) to be involved in a diplomatic solution—it would make sense for the US to take Iran up on that,” Majd added.
But Karim Sadjadpour argues that “successful diplomatic engagement with Iran is hampered by the fact that outside powers — be it the U.S., Russia, or the Arab world — cannot offer Tehran assurances that a post-Assad government in Syria will remain friendly to Iranian interests”:
Ironically, the collapse of the Assad regime would produce a common interest for Washington and Tehran in making sure that radical Sunni Islamists, who hate Shiite Iran even more than America, do not rule Damascus. Until then, as long as Iran sees itself embroiled in a zero-sum game in Syria, a half-way meeting point, however desirable, will likely remain elusive.
Regardless, Juan Cole believes that American intervention will kill any chance of negotiations between the Syrian government and rebels:
By striking Syria, Obama has all but guaranteed that a negotiated solution becomes impossible for years to come. In the absence of serious negotiations, the civil war will continue and likely get worse. The US should give serious thought to what the likely actual (as opposed to ideal) reaction in Syria will be to the landing of a few cruise missiles. The anti-regime elements will celebrate, convinced that it will all be over quickly if the US gets involved. The last thing they will want will be to negotiate with the regime.