"Americans say you should accept what we say in the talks. So this is not negotiation, but a dictatorship. The Islamic Republic and the Iranian nation would stand up against dictatorship," senior Iranian cleric Ahmad Khatami said, as reported by the Mizan news agency.
US President Donald Trump earlier said that anyone doing business with Iran will not be doing business with the US, adding that sanctions imposed on Tehran were "the most biting."
Responding to Trump's statement, Iran's President Hassan Rouhani blamed the US for using "psychological warfare," aiming to "sow division among Iranians."
READ MORE: Unlikely Allies: Will Israel Join 'Arab NATO' Aimed Against Iran?
Washington plans to add Iranian oil and gas to the list during the second phase of sanctions to be reintroduced in November, which is part of US President Donald Trump's May withdrawal from the Iran nuclear deal.