IRNA news agency reports that Ahmadinejad made the plea at a meeting on November 18 with the head of the North Korean Supreme People's Assembly, Choe Thae Bok.
North Korea exploded a nuclear device in October.
Ahmadinejad made no mention of Iran's own nuclear program, which the international community suspects is aimed at developing nuclear arms.
The nuclear programs of both Iran and North Korea were among the subject of talks between U.S. President George W. Bush and Chinese President Hu Jintao on the margins of an Asia-Pacific Economic Cooperation (APEC) summit on November 19.
Bush told Hu that cooperation between China and the United States could help solve the problems posed by Iran's and North Korea's nuclear programs.
Hu called for patience in dealing with Pyongyang.
APEC leaders issued a statement expressing "strong concern" at North Korea's nuclear test and urging Pyongyang to honor commitments not to pursue the development of atomic bombs.