Al Qaeda have been denouncing Iran as yankee imperialist puppets, or some such nonsense. Whilst both Iran and Al Qaeda can broadly be described as Islamists, or Islamic Fundamentalists it would be a mistake to conflate the two or assume that they have common interests. Fanatics hate infidels alright but they really hate heretics, and to Sunni Islamists like Al Qaeda, the Shia Islamists in Tehran are the enemy.
Iran nearly got into a full scale war with Al Qaeda's soulmates, the Taliban, back in the late 1990s after the latter organisation murdered some Iranian diplomats in Afghanistan.
This doesn't mean that there will never be cooperation between the two sets of fanatics, Iran does support the Sunni group Hamas and has been alleged to now be supporting their old adversaries the Taliban in Afghanistan. Al Qaeda on the other hand are too stupid to understand the concept of my enemy's enemy is my friend and prefer to keep blowing up Shia in Iraq rather than allying with them against us. However there is a fundamental tension between the two groups that it may be possible to exploit in the same way that differences between the two communist powers, China and the USSR, were exploited by Nixon back in the 1970s.