Provacative and inadvisable, yes. Act of war, no.
To a small country surrounded by enemies and hated by the world, I would call this an act of war ... but that is just me. LOL!
These ships are likely carrying arms to Syria so they can be passed to Israel's enemies without inspections or any other outside oversight. For all we know they could be weapons of mass destruction. Iran is certainly capable of producing them. The fact is they've been preparing for war for some time.
A freighter might be boarded and inspected.
Who's going to board a war ship and inspect what its carrying?
This is more than provocation.
It is a direct threat that is fulfilling a part of a larger plan.
It depends on what is being transported in those two ships.