Personally I regard the EU refusal to import Iranian oil as a wise decision in the long-term. No one actually wants Iran to get an atom bomb. If that happen, it will have a serious destabilizing effect on the region. It is definitely not in everyone's interest to have another bomb in that country of the world.
I would not agree that the weakness in the major economies may put downward pressure on prices of oil and other commodities. Even though, it is not exactly the situation we are observing now. The European situation is cooling down a bit more rapidly than expected. We also see very positive signs from China and the US economy. Even though, the growth numbers are not that impressive when we look into the details. It is still quite decent growth. It certainly looks better on the macroeconomic global perspective. The basic idea is if there is a downturn in macroeconomic conditions, it will definitely have an impact.