Israeli premier Benjamin Netanyahu has left for New York in an attempt to challenge perceptions that Iran under its new president poses less of a nuclear threat.
"I intend to tell the truth in the face of the sweet talk and charm offensive of Iran," Netanyahu told Israeli public radio as saying as he boarded the plane at Tel Aviv's Ben Gurion airport early on Sunday.
"Telling the truth at this time is essential for world peace and security and, of course, for Israel's security."
He has described the conciliatory speech by Hassan Rouhani, Iran's president, to the UN General Assembly as "cynical" and "full of hypocrisy".
Netanyahu is due to meet US President Barack Obama at the White House on Monday and return to New York to address the UN General Assembly on Tuesday.
Netanyahu has long put what Israel and the West say is a covert Iranian programme to develop a nuclear weapon at the forefront of his security concerns.
Nuclear programme 'important'
Iran denies the charge and in his UN address Rouhani said nuclear weapons had no place in Iran's security and defence doctrine.
The moderate, tasked with easing concerns over Iran's nuclear program, made history on Friday by speaking by phone to US 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.
Hundreds of Iranians cheered Rouhani on his return from New York on Saturday after his historic phone call with Obama, but about 100 hardliners shouted "Death to America" and threw eggs and shoes at his official car leaving the airport, Iranian media reported.
Rouhani said after returning home that he told Obama that Iran's nuclear programme was a right of the Iranian nation and a matter of development.
"But also, and more importantly, it is a matter of national pride for the Iranian people," he said.