I doubt that Iran would close the Strait, any Iranian response to tougher sanctions or an attack would be far more subtle. I would suggest that:
1. Blocking the Strait of Hormuz would be a highly provocative act, it would destroy any goodwill towards Iran by other Middle Eastern nations, particularly the Gulf states. Similarly Russia and China are unlikely to have anything other than an extremely dim view.
2. This type of extreme action would force the West to act. Strikes against targets on the Iranian mainland might become an option. Prudence will demand that Iranian naval, air, and missiles forces are hunted and destroyed.
3. Concentrating large proportions of Iranian forces around or in the Strait will make the task of finding and destroying them easier.
4. The Iranian coast is over 1200 miles long, so why make things easy for the US/West? Why not attack over a larger area? The
Kilo submarines, for instance, would be more likely to survive in the Gulf of Oman or Iranian sea. Dispersed attacks would make things harder to counter.
5. More targeted actions, using weapons aimed an individual ships (tankers going to/from a certain nation, or with a certain nation of registration/flag, or the naval forces of the US or allies). Whilst still an act of war, international opinion will resist an all out assault against Iranian forces. The non reaction to North Korea's sinking of the South Korean warship
Cheonan demonstrates this.
6. If international opinion prevents offensive responses against Iranian forces, Western forces will be on the back foot in defensive roles with restricted ROE.
7. The amount of Host Nation Support provided to the West may be limited, either due to politics (Israeli/US strike first) or for fear of Iranian reprisals - Iran has lots of surface to surface missiles, and has various terrorists as proxies.
There are a lot of open source articles regarding these issues:
Closing Time
US-Iranian Confrontation at Sea
Iranian Mining of the Strait of Hormuz – Plausibility and Key Considerations
A list of vessels attacked during the tanker war
THE TANKER WAR AND THE LESSONS OF NAVAL CONFLICT
Expansion of the tanker war in the Gulf to include Western navies....