Iran doesn't own any of those tankers. We start taking out tankers and insurance rates skyrocket along with oil adversly affecting the world economy including the US (oil is a fungible commdity). So not feasible.
Iran’s fleet of very large crude carriers, or VLCCs, and Suezmax tankers -- the largest that can fit fully-laden through the Suez Canal -- has always played an important role in delivering Iranian crude to customers, but it is increasing as insurers and international shipping companies react to the sanctions snap-back. In April, vessels belonging to the National Iranian Tanker Co. were hauling a little under half of country’s crude and condensate exports. By last month that share had risen to around two thirds.
Iran's Reliance on Own Oil Tankers Grows Even as Flows Slump
https://www.bloomberg.com/news/articles/2018-08-08/iran-forced-to-rely-on-own-crude-tankers-even-as-volumes-fall
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And as for my recommendation to start capturing or sinking Iran's oil tankers driving up the price of oil, that's not necessarily a bad thing for our own oil production, something we're going to need to rely on heavily in case of Middle East production shortfalls - one way or another, a given in our time.