Looking at the Torygraph balance of forces this appears to be an absolutely classic imbalance for assymentric warfare. There may be many more target sets suitable for cruise missiles etc than there are cruise missiles and almost as many targets that are unsuitable for anything larger than a 30mm.
While the size of the country is indeed huge it is nowhere as dense as a similar sized European theatre. To compare war zones, Iran is about four times larger than Iraq and over 2 1/2 times larger than Afghanistan whose population is 30 millions compared with Iran at 78 millions.