Even simpler than that is to quietly sink every tanker that tries to leave Iran. As soon as they pass Oman let ‘er rip. The Israelis already have at least one sub in the hood that could get it done. Boy would that start a bellyache fest. But if the Irans are sending uniformed geniuses to the north Israel border they are begging for a serious hit(s).
Easier, yes. But those ships are owned (and manned) by other countries. Create too much of a stink. Think WWI.
The off-load points, in contrast, are largely manned by Iranians and are Iranian property.
They also don’t move and have the radar signature of, well, a giant metal box.
This is what I would blow up:
http://wiki.openoil.net/index.php?title=Kharg_Oil_Terminal
and this:
http://www.arabianoilandgas.com/article-12195-iran-launches-floating-export-terminal/
Their economy would cease.