The European Union says it's sticking to the 2015 nuclear deal with Iran, despite the US' withdrawal.
In a statement, it said it ''deeply regrets'' the re-imposition of US sanctions.
Iran's foreign minister says his country will overcome the economic measures and won't be changing its regional policies.
In Tehran, carpet sellers, car dealers and foreign exchange outlets will be the first in line to feel the effects.
Al Jazeera's Zein Basravi reports.
