UNITED NATIONS — Iran’s new president told world leaders Tuesday that the biggest danger in the Middle East is chemical weapons falling into the hands of “extremist terrorist groups” in Syria and he blamed the countries backing the opposition for fueling the civil war there.

The comment by Hasan Rouhani, in his first speech to the United Nations General Assembly, closely mirrored language used by the Iranian-allied Syrian regime, which refers to the opposition as terrorists. The U.S. and its allies, including Gulf nations Saudi Arabia and Qatar, have been supplying the Syrian opposition with weapons, aid and training.

Rouhani praised Syria’s willingness to accept the international treaty barring the use of chemical weapons. And without naming nations, he warned that the “illegitimate and ineffective threat” to use military force in Syria “will only lead to further exacerbation of violence and crisis in the region.”

Just a few weeks ago, President Barack Obama was considering launching a military strike on Syria to retaliate for a chemical weapons attack on Aug. 21 the U.S. blamed on Bashar Assad’s regime. But a U.S.-Russia deal to put Syria’s chemical weapons under international control averted military action, at least for now.

Even as he sided with the Assad’s regime, Rouhani also sent signals that Iran might be ready to negotiate with the West on its disputed nuclear program and talk to the United States after decades of frozen relations. He said “peace is within reach.”

Rouhani spoke hours after Obama also addressed the General Assembly, saying the U.S. prefers to resolve its concerns over Iran’s nuclear program peacefully but is determined to prevent Tehran from developing a nuclear weapon.

Obama said he was “encouraged” that Rouhani received a mandate from the Iranian people to pursue a more moderate course, but added “the diplomatic road must be tested.” Rouhani’s “conciliatory words will have to be matched by actions that are transparent and verifiable,” Obama said.

Rouhani called his election over the summer a “wise choice of hope, rationality and moderation” and said every issue can be resolved through mutual respect and rejection of violence and extremism.

He is considered a relative moderate amid the hard-line clerics who control Iran. But Supreme Leader Ayatollah Ali Khamenei holds the real power, deciding all important matters of state including the nuclear program.

Elements of Rouhani’s speech were reminiscent of the anti-American rhetoric of his predecessor, Mahmoud Ahmadinejad. He was critical of how America projects power and called for a new world order without the U.S. as a superpower.