Nobody can underestimate Iran as a middle size power in the Middle East. Iran has a population of over 80 million with a relatively developped industrial system that is able to produce short to long range ballistic missiles that may threaten large moving targets on the ocean and fixed targets in the region. If it is attacked, Iran must retaliate via launching these missiles to strike its intended targets. That could raise the scale of a war that would extend to the region and beyond.
Another factor should be considered before any attack against Iran that has a solid support from its ally - the Superpower Russia. It is likely that Russia would be involved in the war given Iran is attacked. This condition has to be thoroughly investigated before any military action is taken, although double US aircraft carriers are moving around in the sea not far away the Iranian coasts.
However, a direct strike on Iran soils is unlikely to take place because of analysis mentioned above.