President Mahmoud Ahmadinejad has dismissed the new UN sanctions over Iran's nuclear programme as a "used handkerchief" fit for the dustbin.
Earlier, the UN Security Council voted to impose a fourth round of sanctions on Tehran for failing to halt its nuclear enrichment programme.
They include tighter finance curbs and an expanded arms embargo, but not the crippling sanctions the US had wanted.
Iran denies building nuclear weapons, insisting it seeks only atomic energy.
US President Barack Obama said the sanctions sent an unmistakable message about the determination to stop the spread of nuclear arms.
At a meeting at the UN in New York on Wednesday, the Security Council voted by 12 votes to two in favour of a fourth round of coercive measures.
Brazil and Turkey voted against the sanctions, while Lebanon abstained. They argued that the sanctions were counter-productive and endangered a diplomatic solution.
Later, Mr Ahmadinejad was quoted by Iran's Isna news agency as saying: "I gave one of the [world powers] a message that the resolutions you issue are like a used handkerchief which should be thrown in the dustbin.
"They are not capable of hurting Iranians," he added.
The most significant parts of the resolution create a legal basis to restrict the supply of goods that Iran wants for its alleged nuclear missile programmes, says the BBC's Middle East editor, Jeremy Bowen.
Our correspondent says the resolution singles out the Iranian Revolutionary Guards, who run much of the economy - including the national shipping line which Western diplomats say is trying to evade sanctions by setting up front companies.
The sanctions also prohibit Iran from buying heavy weapons such as attack helicopters and missiles.
They toughen rules on financial transactions with Iranian banks, and increase the number of Iranian individuals and companies that are targeted by asset freezes and travel bans.
But the sanctions were passed after being watered down during negotiations with Russia and China on Tuesday.
In the end there were no crippling economic sanctions and no oil embargo.
The vote for sanctions came almost 18 months after US President Barack Obama promised a new strategy of engagement with Iran when he took office.
Yet the US eventually pushed for tougher sanctions.
Mr Obama said the sanctions did "not close the door on diplomacy" and he urged Iran to "choose a different and better path".
China's UN ambassador Zhang Yesui said the sanctions were trying to prevent nuclear proliferation and would not hurt "the normal life of the Iranian people".
But Turkey and Brazil said the sanctions may have closed the door to negotiations just as it was opening.
They insisted a deal they recently brokered with Iran on a nuclear fuel exchange had provided the pathway back to talks.
"[The sanctions] will most probably lead to the suffering of the people of Iran and will play into the hands of people on all sides who do not want dialogue to prevail," said the Brazilian ambassador to the UN, Maria Luiza Ribeiro Viotti.
The two "no" votes were the strongest opposition yet in four rounds of sanctions, weakening the international unity the Americans have tried to build to isolate Iran.
Welcoming their votes, Iran's UN ambassador vowed that sanctions would not stop Tehran from what he said was its peaceful pursuit of nuclear energy.
"No amount of pressure and mischief will be able to break our nation's determination to pursue and defend its legal and inalienable rights," Mohammad Khazaee told the BBC.
"Iran… never will bow to the hostile actions and pressures by these few powers and will continue to defend its rights."
The BBC News website's world affairs correspondent, Paul Reynolds, says this fourth round of sanctions is unlikely to have any more effect on Iranian policy than the first three.
Iran's vital economic interests have not been targeted and Tehran has already developed systems of evasion, he says.
Three earlier rounds of UN sanctions blocked trade of "sensitive nuclear material", froze the financial assets of those involved in Iran's nuclear activities, banned all of Iran's arms exports and encouraged scrutiny of the dealings of Iranian banks.