That's part of a larger goal of politically subduing them. Should that fail, expect a full blockade of all Iranian ports and the destruction of all Iranian pipelines...and the destruction of any refining capacity.
Should the Iranians shoot in earnest or try to close the Gulf, they'll be decapitated while the blockade continues.
We have the ability to drive this to closure through blockade and regime decapitation...which includes the destruction of all Iranian military assets.
Iran imports 100 percent of its gasoline and other refined petroleum products. A few weeks of blockade would do wonders.