"It is a piece of torn paper ... by which they aim to scare Iranians... It is in the Westerners' interest to live with a nuclear Iran," Ahmadinejad said in a speech at the former American embassy in Tehran on Friday.
Ahmadinejad also told countries that backed the UN resolution to abandon attempts to persuade Iran to give up its nuclear programme.
"Give up this muppet game. You cannot send secret friendly messages to us and at the same time show your teeth and claws. End this dual game," Ahmadinejad said, according to Iran's IRNA news agency.
Peaceful nuclear activities
Ehud Olmert, the Israeli prime minister, appeared this month to abandon Israel's long-standing policy of ambiguity on nuclear weapons when he listed Israel among countries that possess them.
His office said his comments were misinterpreted.
Reacting to the Security Council vote, the Iranian foreign ministry said that the government will defy the resolution and continue enriching uranium.
"Iran considers the new UN Security Council resolution ... an extra-legal act outside the frame of its responsibilities and against the UN Charter," the statement said.
"The Iranian nation, relying on its national capabilities and within the framework of its rights stipulated in the nuclear Non-Proliferation Treaty, will continue its peaceful nuclear activities."
Javad Zarif, Iran's representative at the UN, made a speech in response to the sanctions which was filled with lists of grievances: allegations of war crimes and nuclear irresponsibility by Israel, Iranian proposals he says were ignored by the Europeans and Americans, and crimes against Iran he said were ignored by the Security Council.
Zarif also questioned the sincerity of the Security Council's claim that it wanted Iran to suspend enrichment in order to build confidence and trust between Iran and the international community.
The United States' "stated objective has always been to use the council as an instrument of pressure and intimidation to compel Iran to abandon its rights", he said.
"Knowing their bright recent history, we can all assume what the unstated objective is."
Iran has said it intends to expand its enrichment programme to 54,000 centrifuges, which spin uranium gas into enriched material to produce nuclear fuel.
Iranian nuclear officials say 54,000 centrifuges would produce enough enriched uranium to fuel a 1,000-megawatt reactor, such as the one Iran has built with Russian assistance at Bushehr, in southern Iran.
The reactor is due to begin operating next year.
Members of the Security Council said the resolution's intent is to persuade Iran to suspend uranium enrichment and submit to inspections.
If the IAEA is satisfied with Iran's compliance, the resolution says, the sanctions will be suspended to allow for a negotiated, diplomatic settlement.