He also vowed that Iran will retaliate should its ships be searched over suspicions that the cargo may violate the new sanctions approved by the U.N. Security Council earlier this month.
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The European Union and U.S. Congress followed with new punishing measures of their own to discourage the Iranian government from continuing its uranium enrichment program, which they fear could be used to produce a nuclear weapon.
Iran insists its program is for peaceful purposes.
Ahmadinejad accused the world powers of approving the latest sanctions to give them the upper hand in talks over the issue.
"We call this bad behavior," he said, adding talks on the issue would be postponed until the end of the Iranian month of Mordad, which would be about Aug. 20. "This is a fine to punish them a bit so that they learn the custom of dialogue with our nation."
The Iranian leader also set three conditions for an eventual resumption of talks, saying countries who want to participate should make clear whether they oppose Israel's purported atomic arsenal, whether they support the Nonproliferation Treaty and whether they want to be friends or enemies with Iran.
However, he said, participation in the talks was not contingent on the answers.
The U.S. and its allies accuse Iran of seeking to use its civilian nuclear program as a cover to develop atomic weapons. Iran has denied the charge.
The new U.N. sanctions call for an asset freeze of another 40 additional companies and organizations, including 15 linked to Iran's powerful Revolutionary Guard and 22 involved in nuclear or ballistic missile activities. The resolution also bans Iran from pursuing "any activity related to ballistic missiles capable of delivering nuclear weapons."
It also bars Iranian investment in activities such as uranium mining, and prohibits Iran from buying several categories of heavy weapons, including attack helicopters and missiles.
The sanctions, the fourth imposed by the U.N., came after last year's push to get Iran to accept a U.N.-drafted plan to swap its low-enriched uranium for higher-enriched uranium in the form of fuel rods, which Tehran needs for a medical research reactor.
At the time, the swap would have significantly reduced Iran's low-enriched uranium stockpile and delayed any weapons-making capabilities.
Instead, Iran opted for an alternative plan backed by Turkey and Brazil that included the uranium-for-rods exchange but didn't mandate a halt on Iran's enrichment process and fell short of U.N. demands.
Ahmadinejad also suggested that other countries should be invited into the talks, which currently consist of the permanent members of the U.N. Security Council and German - a possible reference to Turkey and Brazil.
Iran's elite Revolutionary Guard, the country's most powerful military force, has warned in recent days that it will retaliate should Iranian ships be searched.
Ahmadinejad reiterated that warning.
"We reserve the right to retaliate," Ahmadinejad said. "We were not interested in getting to this stage. But if some insist (on going in this direction), experience has shown that we can defend our rights. They will strongly regret any action they may take."
Ahmadinejad also scoffed at assertions Sunday from U.S. intelligence chief Leon Panetta that Iran had enough material to make two nuclear bombs.
He said stockpiling nuclear weapons was "politically retarded" and warned over possible accidents with the U.S.'s own vast nuclear stockpile.
"A country that cannot cap an oil well, how can they stockpile thousands of atomic bombs inside the U.S. and other countries?" he asked, referring to the oil gushing into the Gulf of Mexico.
He offered the help of Iranian experts to contain the breach.