U.S. President Donald Trump hit out at Iran and promoted his America First policies as he addressed the 74th United Nations General Assembly (UNGA) on Tuesday morning New York time.

Second to the podium after Brazilian President Javier Bolsonaro, Trump insisted he was looking for "partners not adversaries" but warned Tehran that he would "never allow" it to obtain a nuclear weapon and cautioned further sanctions could be imposed.

"All nations have a duty to act. No responsible government should subsidize Iran's bloodlust," he said. "As long as Iran's menacing behavior continues, sanctions will not be lifted. They will be tightened."

The president, who described Iran as the world's number one state sponsor of terrorism before accusing it of "fueling" wars in Syria and Yemen, called on "Iran's leaders to focus on building up their own country."

"America is ready to embrace friendship with all who genuinely seek peace and respect," he added. Tensions between Iran and Washington have grown since Trump withdrew the U.S. from the Iran nuclear deal in 2018.

'Future does not belong to globalists'

Trump began his speech by describing the U.S. as the world's "most powerful nation," criticizing "endless wars" and defending his America First approach.

"If you want freedom, take pride in your country. If you want democracy, hold on to your sovereignty. If you want peace, love your nation," he said.

"The future does not belong to globalists; the future belongs to patriots."

He went on to take swipes at Democratic presidential rivals, with attacks on socialism and open-border migration policies and hit out at the international trading system with a call for "drastic change" at the World Trade Organization.

Bolsonaro rejects Amazon criticism

Bolsonaro earlier strongly rejected criticism over recent fires in the Amazon, hitting back at "sensationalist attacks we have suffered" from international media and claiming some countries had been "disrespectful" and "colonialist" in their condemnation.

He insisted the rainforest was "almost pristine, and untouched," adding that Brazil was "one of the countries that most protect the environment." The BBC has reported that more than 80,000 fires have broken out in the Amazon rainforest so far this year.

Secretary-General Antonio Guterres stressed the importance of striving for gender equality in an opening statement on Tuesday morning, before UNGA President Tijjani Muhammad-Bande commenced the General Debate.

Representatives of all 193 UN members are expected to address the UNGA over the coming days.