Of course, this could be a bluff. But then you have to ask yourself, why bluff about this? What would Iran's motive be for claiming to have intel on Israel that it doesn't really have? Bluster? Well, Iran would have to know that such a claim will further agitate the West. Is that what it wants? If so, why?
Or, are the simply telling the truth. Again, you'd have to ask why they'd do that. If the downed drown did provide this type of intelligence, why let the world know you have it? If I had to guess, I'd guess it's a bluff. But as I said above, the motive for such a bluff remains unclear to me.