"Americans and Zionists are the sole audience of a play they have commissioned and sold out. A nauseating play is performed.
Ahmadinejad also hit out at comments made by US President Barack Obama and the British government, who have strongly criticised Iran's crackdown on protesters.
"We have advised them repeatedly but it looks as if they insist on being humiliated, we are sure they will be humiliated more than their predecessors," he said.
French President Nicolas Sarkozy added his voice to the criticism, condemning the "bloody crackdown" on opposition demonstrators and calling for the release of those arrested by the security forces.
France urged "a halt to the violence, the freeing of all imprisoned opposition members and the respect of human rights," said a statement on his website.
Sarkozy also called for an end to the arrests, which he said were only making the situation worse.
But Iranian cleric Ayatollah Abbas Vaez Tabasi branded opposition leaders as "enemies of God" whose punishment under Islamic sharia law is death, Fars news agency reported.
"Leaders of sedition are Mohareb (enemies of God)," said Vaez Tabasi, the representative of Iran's supreme leader Ayatollah Ali Khamenei in Khorasan province.
"In our judiciary, the verdict for Mohareb is clear and they deal with it within law," he said.
His statement, the strongest yet against opposition leaders, came after speaker Ali Larijani said parliament wants the authorities to arrest "those who insult religion and impose the maximum punishment."
Parliament also condemned "disgusting comments" by Western governments about Sunday's unrest, after they unanimously denounced the deadly crackdown in the Islamic republic.
In that vein, Iranian Foreign Minister Manouchehr Mottaki lashed out at Britain.
"If they (the British) do not stop their absurd comments, they will be slapped in the mouth," Mottaki was quoted by the ISNA news agency as saying.
Tehran had already summoned British envoy Simon Gass, while a pro-government website said a Briton was among those arrested at the demonstrations.
On Monday, British Foreign Secretary David Miliband had hailed the "great courage" of Iranian opposition supporters.
In London, the foreign office said Gass had "responded robustly... and reiterated (Miliband's) comments that the Iranian government must respect the human rights of its own citizens.
People had taken to the street on the holy day of Ashura, which commemorates the 7th century murder of Shiite Islam's holiest martyr, Imam Hussein, the grandson of the Muslim Prophet Mohammed.
Eight people were killed as security forces used teargas, batons and eventually live rounds to push back thousands.
Iran rounded up scores of opposition figures and dissidents after Sunday's protests and on Tuesday several reformist journalists and activists were also arrested, reports said.
Hardliners have reacted angrily to what they see as "desecration" of Ashura by opposition supporters and have staged counter-demonstrations calling for tough action against protesters, state media reported.
More pro-government marches are planned for Wednesday around the country.
The opposition, in turn, has excoriated the authorities for resorting to violence on Ashura, a day when custom prohibits it.
MPs, who accused the protesters of being "counter-revolutionaries" and "anti-religion," took a softer stance towards opposition leaders, who reject Ahmadinejad's June re-election as fraudulent. They urged them to distance themselves from the protests.
"We expect these gentlemen who had complaints in the election to wake up and clearly separate their path from this wicked movement, not to come out and issue statements again and make the air dustier."
In a defiant reaction, Iran's leading reformist party condemned violence against demonstrators and backed the protests.
The Islamic Iran Participation Front, which is allied with opposition leader Mir Hossein Mousavi, called on the government to "reconcile with protesters and stop breaking the law, deception and tyranny."
On another front, Nobel peace laureate Shirin Ebadi said intelligence agents had arrested her medical professor sister, Dr Nooshin Ebadi, on Monday.