Prime Minister Binyamin Netanyahu left for New York overnight Saturday in a bid to challenge perceptions that Iran under its new president poses less of a nuclear threat than before.
"I intend to tell the truth in the face of the sweet talk and charm offensive of Iran," AFP quoted Netanyahu as saying as he boarded the plane at Tel Aviv's Ben Gurion Airport.
"Telling the truth at this time is essential for world peace and security and, of course, for Israel's security," noted Netanyahu.
On Monday, Netanyahu will meet U.S. President Barack Obama at the White House, then return to New York to address the General Assembly on Tuesday.
Netanyahu has long put what Israel and the West say is a covert Iranian program to develop a nuclear weapon at the forefront of his security concerns.
Iran denies the charge and in his UN address, Rouhani said that "nuclear weapons... have no place in Iran's security and defense doctrine."
The self-styled moderate, tasked with easing concerns over Iran's nuclear program, made history on Friday by speaking by phone to U.S. President Barack Obama, in the first contact between the countries' leaders since the 1979 Islamic revolution.
Israeli media said that Netanyahu had instructed his ministers and senior officials not to comment on the call.
Israel has several times warned that Rouhani is "a wolf in sheep's clothing" who would "smile and build a bomb".