If Iran have assets worldwide, US and EU would already freeze them as they did to Gadafi, but they can't, because they are in Iran. Iran evacuate assets home same as Venezuela did.Iran has assets worldwide that could be seized and serve to repare the prejudice.
Iran does have assets worldwide and the position of some of them is dynamic: Iranian ships and tankers could be seized at any port. Same thing for commercial planes at international airports...
If Iran breaks the contracts, the price it will pay such thing could be very heavy.
Also, freezing of banking assets is one thing. Seizure of the assets is quite another.
Iam expecting Monday to be a tough day for all the European countries...
This is not the same thing. If I don't buy Apple, because I don't have money it's not embargo, but my financial decision. If state put a law, which forbid me to buy Apple, this is embargo and I will be punished if I buy it. Law forbidding buying goods from someone is act of hostilities, because it gives punishments if you still buy those goods. EU start hostilities with Iran. If EU didn't impose embargo, Iran would still sell oil and gas to EU.
I do not claim I do. I am just expressing my personal opinion at the moment. I can call a friend for a more professional take on such a matter.
If there is an existing contract to supply a commodity that is done on either state level or company to company level. There are always provisions and clauses in such a contract and penalties of course.
I can not imagine that all long term contracts with EU countries would all suddenly end in July. There might be some contract breaking on the EU side.