Trump reimposes sanctions on Iran

US President Donald Trump yesterday warned the world against doing business with Iran as he hailed the "most biting sanctions ever imposed", triggering a mix of anger, fear and defiance in Tehran.

"The Iran sanctions have officially been cast. These are the most biting sanctions ever imposed, and in November they ratchet up to yet another level," Trump wrote on Twitter.

"Anyone doing business with Iran will NOT be doing business with the United States. I am asking for WORLD PEACE, nothing less."

Within hours of the sanctions taking effect, German carmaker Daimler said it was halting its business activities in Iran.

Trump's May withdrawal from a landmark 2015 nuclear agreement had already spooked investors and triggered a run on the Iranian rial long before nuclear-related sanctions went back into force.

"I feel like my life is being destroyed. Sanctions are already badly affecting people's lives. I can't afford to buy food, pay the rent," said one construction worker on the streets of the capital.