European diplomats have agreed in principle to ban Iranian oil imports to the EU. The decision is now in the hands of their governments, which are not likely to enact such a ban anytime soon.
The proud Iranians won’t sacrifice their nuclear ambitions because of an embargo. A ban would also be ineffective, as Iran could continue exporting oil to India and China, and on the black market. It could also re-export through Russia.
If Israel bought Iranian oil for years through Glencore, despite all the Muslim embargoes, how do we expect an EU embargo to work any better?