North Korea is under USA and United Nations sanctions over its nuclear weapons programme.
Mark Dubowitz, chief executive of the Foundation for Defense of Democracies, said the first wave of sanctions targeting Iran's automotive sector as well as gold, steel, and other metals will add fuel to the protests.
Donald Trump claimed they were "the most biting ever imposed" and warned that in November, sanctions would "ratchet up to yet another level" with an embargo on Iranian oil and blanket sanctions on Iranian banks.
U.S. sanctions on Iran's energy sector are to be re-imposed after a 180-day wind-down period ending on November 4.
"NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE", Trump wrote.
Gholamali Khoshroo argues in a commentary published by the Guardian on Wednesday that by abrogating a multilateral 2015 nuclear deal and imposing new sanctions on foreign companies doing business with Iran, the Trump administration is also reneging on UNSC resolution 2231.
"China has consistently opposed unilateral sanctions and long-armed jurisdiction", the Chinese foreign ministry said in a faxed statement to Reuters, responding to questions on the new U.S. sanctions and Trump's threats on firms doing business with Iran.
"The US withdrawal from JCPOA and re-imposition of its sanctions is a serious breach of its legal obligations under the United Nations Charter, which entails its worldwide responsibility".
European countries, hoping to persuade Tehran to continue to respect the deal, have promised to try to lessen the blow of sanctions and to urge their firms not to pull out.
"Anyone who knows anything about Iran's behavior knows that the Iranians escalate when they sense American mush and they back down when they perceive American steel".
Turkey's Energy Minister Fatih Donmez also said that his country would continue to buy natural gas from Iran.
However, a senior USA official said it was "not particularly concerned" by the move because many major firms had already announced they were pulling out of Iran.
The United States will not be able to prevent Iran from exporting oil, Iranian Foreign Minister Mohammad Javad Zarif was cited as saying by an Iranian newspaper on Wednesday.
His trip came on the same day that the USA restored sanctions on the Islamic Republic.
"They can not think that Iran won't export oil and others will export.".
Already facing broad economic fallout as their currency implodes, Iranians are wondering how the next phase of the crisis in United States relations will play out - and what, exactly, America's long-term strategy is toward their country.