I think war is very unlikely.  This actually looks more like a dispute between Israel and the US than it does between Iran and the US.  In order to put the provincials -- Israel -- in their place, Panetta had to tell the Israelis that the big boys would take care of their bully problem if it ever came to that, telling Israel to go back to the playroom.  Israel was slapped down, but that necessarily invokes a symbolic response from Iran for being portrayed once again as the bully.  But neither side, nor factions within the governments of either side, has anything to gain from a war with Iran at this time.