Iran's President Hassan Rouhani said the Islamic republic "will proudly bypass sanctions" by the United States that took effect on Monday targeting the country's oil and financial sectors.
"I announce that we will proudly bypass your illegal, unjust sanctions because it's against international regulations," Rouhani said in a televised speech.
"We are in a situation of economic war, confronting a bullying power. I don't think that in the history of America, someone has entered the White House who is so against law and international conventions," he added.
The renewed US sanctions aim to significantly curb Iran's oil exports and cut it off from international finance, and follow US President Donald Trump's controversial decision in May to abandon the multi-nation nuclear deal with Tehran.
Meanwhile, Iran’s Foreign Minister Barham Qasemi said the sanctions are part of a psychological war launched by Washington against Tehran but these will fail.
“(US President Donald) Trump's administration is addicted to imposing sanctions ... America’s economic pressure on Iran is futile and part of its psychological war against Tehran,” Qasemi told a weekly news conference.
But US Treasury Secretary Steven Mnuchin said in an op-ed in the Financial Times that tough pressure is "an important step towards holding the world’s largest state sponsor of terror accountable for its malign behavior, human rights abuses, ballistic missiles development, and systematic efforts to exploit the global financial system to fund its revolutionary ambitions."