Iranian President Hassan Rouhani addresses the 73rd session of the United Nations General Assembly, Tuesday, Sept. 25, 2018 at U.N. headquarters. (AP Photo/Mary Altaffer)

UNITED NATIONS - Iranian President Hassan Rouhani on Tuesday criticised Washington for its hostile policy toward his country and said the U.S. approach was doomed to fail.

Rouhani, in a speech to the United Nation General Assembly, said the United States had waged "economic war" against Iran by reimposing unilateral sanctions, which were lifted under the country's 2015 multinational nuclear deal in return for Tehran curbing its nuclear work.

"The United States policy vis-à-vis the Islamic Republic of Iran has been wrong from the beginning, and its approach of resisting the wishes of the Iranian people as manifested in numerous elections is doomed to failure," Rouhani said.

President Donald Trump pulled the United States from the pact in May and his administration reimposed sanctions on Iran in August. Harsher sanctions on Iran's oil and banking sector are expected in November.

"The economic war that the United States has initiated under the rubric of new sanctions not only targets the Iranian people but also entails harmful repercussions for the people of other countries, and that war has caused a disruption in the state of global trade," Rouhani said.

"What Iran says is clear: no war, no sanctions, no threats, no bullying; just acting according to the law and the fulfillment of obligations."

Mounting pressure from the Trump administration combined with discontent among many Iranians at the state of the economy are rattling the Islamic Republic, with little sign that its leaders have the answers, officials and analysts say.

The rial has lost 40% of its value against the U.S. dollar since April and Iran has blamed U.S. sanctions for the currency's fall, saying the measures amount to a “political, psychological and economic” war on Tehran.

To pile on the pain, Washington says all countries must end crude imports from Iran by Nov. 4, hitting the oil sales that generate 60 percent of the country’s income. Iran says this level of cuts will never happen.

Trump, in his annual U.N. speech, said he would keep up economic pressure on Tehran to try to force a change in its behavior. But Rouhani said Iran had no intention of succumbing to the U.S. pressure.

"The United States’ understanding of international relations is authoritarian ... Its understanding of power, not of legal and legitimate authority, is reflected in bullying and imposition," Rouhani said.

"No state and nation can be brought to the negotiating table by force."

Rouhani also said Iran believed in setting up a collective mechanism for the Persian Gulf with the presence and participation of all regional countries.

Iran and U.S.-backed Saudi Arabia are involved in proxy conflicts across the region, from Syria to Lebanon.