Hassan Rouhani also said that, had Iran wanted weapons of mass destruction, it would be easier for it to make chemical or biological weapons. He made the comments Saturday while addressing Iran's Defense Ministry officials.
Rouhani said that Iran's "beliefs" and commitment to "ethical principles" prevent it from making a bomb.
Iran's Supreme Leader Ayatollah Ali Khamenei has already issued a religious decree banning the production and use of nuclear weapons. He says having such arms is a sin.
The US and its allies fear that Iran seeks to develop the ability to make a nuclear weapon, should it want one. Iran denies the charge.
Earlier in the week, a Reuters report revealed that the International Atomic Energy Agency (IAEA) had shelved a major report on Iran that might have revealed more of its alleged bomb-relevant research, but held off because of the warming relations between Iran and the West.
On Friday, Israel urged the UN nuclear watchdog agency to go public with all information it has regarding suspicions that Iran researched how to build an atomic bomb.
"The role of the IAEA is to expose to the international community all information regarding military aspects of the Iranian nuclear project, and not to withhold it for reasons of diplomatic sensitivity," Israeli Strategic Affairs Minister Yuval Steinitz said in a statement.