Jane's Fighting Ships, 2004-2005 - Iran
Strength of the Fleet
Submarines - 3
Midget Submarines - 1 (3 in building)
Frigates - 3
Corvettes - 2 (3 in building)
Fast Attack Craft, Missile - 20
Large Patrol Craft - 8
Coastal Patrol Craft - 123+ (12 in building)
Landing Ships (Logistic) - 7
Landing Ships (Tank) - 6
Hovercraft - 6
Minesweepers, Coastal - 3
Replenishment Ship - 1
Supply Ships - 1
Support Ships - 7
Water Tankers - 4
Tenders - 13
Presuming they top off their bunkers at say, Egypt, and made a beeline straight for Havana, the only major vessels with the legs to make the trip would be their three aged Kilo-class submarines, with a 7 knot cruising speed range of 6000nm.
Their next longest ranged vessels are: 3 Alvand (Vosper Mk5) class guided missile frigates (range 3650nm), 2 Bayandor (PF 103) class corvettes (range 2400nm), and 10 Kaman (Combattante II) class fast attack craft, missile (range 2000nm).
Even if they tried to say, top off at Freetown, Sierra Leone, and then made for El Guamache, Venezuela, their frigates would still not have the legs for making the short mid-Atlantic hop (nominally 3013nm) solo.
Interestingly I was mostly incorrect regarding their UNREP capability (though their actual proficiency at such maneuvers in a blue water environment remains seriously questionable). The Iranian's possess a grand total of three vessels that could potentially serve as oilers: 2 AORLH Fleet Supply Ships, range 3500nm at 16 knots, displacement 4,673 tons full load and 1 AORH Replenishment Ship, range unlisted, top speed 21.5 knots, displacement 33,014 tons full load. For a practical comparison a US Navy AOEHM Fast Combat Support Ship (Sacramento class) has a nominal full displacement of 53,600 tons and a range of 10,000nm at 17 knots or 6,000 nm at 25 knots.
So in final summary about Iran driving around our coast.... *yawn* think you guys could kill some FARC drug smugglers while you're down here? I'm gonna be over there taking a nap.