President Obama on Tuesday in an address to the United Nations said he would respond to recent diplomatic overtures from Iran by directing Secretary of State John Kerry to pursue nuclear talks with Tehran.

“I firmly believe the diplomatic path must be tested,” Obama told the UN General Assembly meeting.

Obama’s comments come after the election of new Iranian President Hassan Rouhani.

Rouhani is seen as a moderate and in an interview with NBC News pledged that he would not build nuclear weapons. In a Washington Post op-ed last week he also called for “constructive” dialogue between the U.S. and Iran.

Iran watchers say Rouhani hopes to lift international sanctions which have had a crippling effect on his country’s economy.

Iran insists its nuclear program is used for peaceful energy purposes, but the U.S., UN and European Union charge that Iran is developing weapons capabilities.

“We are encouraged that President Rouhani received from the Iranian people a mandate to pursue a more moderate course,” said Obama on Tuesday, acknowledging Rouhani’s efforts to change the tone of U.S.-Iran relations.

But Obama also struck an equally firm message and said the U.S. will not waiver in preventing Iran’s pursuit of nuclear arms.

Obama said Tehran must prove it can be trusted by taking actions to prove their commitment.

“To succeed, conciliatory words will have to be matched by actions that are transparent and verifiable,” he said. “After all, it's the Iranian government's choices that have led to the comprehensive sanctions that are currently in place.”

Rouhani will address the UN later Tuesday.

The White House has said they are open to a meeting between the two world leaders, but that none has been scheduled.

Kerry is slated to meet Iran's foreign minister next week, the highest level meeting between the two nations since the 1979 Iranian revolution.