Washington:
The White House says it hopes Iran's new president will "heed the will" of the voters and make choices that will "lead to a better life" for Iranians.
Hasan Rouhani took the oath of office on Sunday.
White House press secretary Jay Carney says in a statement that Rouhani's inauguration gives Iran a chance "to act quickly" to address international concerns about the country's disputed nuclear program.
The US and its allies contend that Iran is pursuing nuclear weapons, but Tehran denies that.
The White House says Rouhani will find "a willing partner" in the US if his government decides "to engage substantively and seriously" in honoring its international obligations and works toward a peaceful solution to the nuclear issue.