"Fundamentally we do not take seriously the threats of the Zionists. ... We have all the defensive means at our disposal and we are ready to defend ourselves," Ahmadinejad said.
He is in New York to attend the U.N. General Assembly. His speech is scheduled for Wednesday.
On Sunday, U.N. Secretary-General Ban Ki-moon met with Ahmadinejad and warned him of the dangers of incendiary rhetoric in the Middle East. Ahmadinejad did not heed the warning.
Ahmadinejad alluded to his previous rejection of Israel's right to exist. "Iran has been around for the last seven, 10 thousand years. They (the Israelis) have been occupying those territories for the last 60 to 70 years, with the support and force of the Westerners. They have no roots there in history," he said, speaking to reporters through an interpreter.
The modern state of Israel was founded in 1948.
"We do believe that they have found themselves at a dead end and they are seeking new adventures in order to escape this dead end. Iran will not be damaged with foreign bombs," Ahmadinejad said, referring to Israel.
"We don't even count them as any part of any equation for Iran. During a historical phase, they represent minimal disturbances that come into the picture and are then eliminated," Ahmadinejad added.
In 2005, Ahmadinejad called Israel a "tumor" and echoed the words of the former Iranian Supreme Leader, Ayatollah Ruhollah Khomeini, by saying that Israel should be wiped off the map.