does policemen shooting at you when you don't listen to his orders is considered terorism? i would say its just enforcing tax collection.
For Iran's toll system to work, they would need to strike at ships sailing in Omani territorial waters, which is an act of war.
the alternative is that oman and many others can also do the same thing, and the lot of states interested in trade in the area need to get together an negotiate a setup that everyone can agree to