The resolution noted with "serious concern" that Iran had constructed a uranium enrichment facility at Qom in breach of its obligations to suspend all enrichment.
It added that Tehran's failure to notify the IAEA of the new facility until September 2009 was also inconsistent with Iran's obligations.
Hooman Majd, an Iranian-American writer, said Obama was under immense pressure to serve interest groups with respect to Iran's nuclear programme.
"I think a lot of Iranians would agree [with Ahmadinejad] - even on the reform side - that the US and Barack Obama, in particular, is under tremendous pressure by various interest groups to not deal with Iran or to deal with Iran differently," Majd told Al Jazeera.
He said there were those telling the president "not to negotiate because negotiation is fruitless in the minds of many - right-wing Americans, neocons and the Israeli lobby. There is all kinds of different areas where Obama has to be very careful".
Ahmadinejad took centre stage at the opening of the month-long debate on how to stop the spread of nuclear weapons.
He set a defiant tone at the conference on Monday, saying that the US "has never respected any of its commitments" on nuclear weapons.
Washington, he said, had offered not "a single credible proof" to back claims that his country was developing nuclear weapons.
Iran insists it is enriching uranium for purposes of developing nuclear energy for civilian use, but the West suspects it is seeking to develop a nuclear bomb.
Al Jazeera's Kristen Saloomey, reporting from the summit, said: "We've seen sympathies for comments from Mahmoud Ahmadinejad from countries who themselves are pursuing nuclear technology for peaceful purposes and want to develop their nuclear reactors."
But she added that the US, which released previously classified statistics on the size of its nuclear arsenal as Ahmadinejad delivered his speech, had been praised for the move.
The US has 5,113 nuclear warheads in its stockpile, the defence department disclosed on Monday.
UN Security Council powers met on Tuesday to discuss ways to punish Tehran as a final document detailing ways to achieve goals of checking the spread of nuclear weapons was being drafted.
US officials have said they will be looking to isolate Iran and to produce an unofficial document calling for stricter enforcement of the NPT, which requires signatories to abandon nuclear weapons.
The document could be signed by the overwhelming majority of signatory countries, but because it requires a consensus of all parties - including Iran - it would be highly unlikely to censure Tehran and could block consensus, analysts said.
Our correspondent added that the "document ... calls on Israel to sign up and join the NPT. Israel is widely believed to have nuclear weapons but has not confirmed or denied their existence".
"By signing up to the NPT, they would be required to do that. Of course, other countries as well are being asked to do that - India and Pakistan are also nuclear states who have not joined the NPT," she said.
Ahmadinejad, who accused the US of not only using nuclear weapons but also threatening to use them, drew sharp criticism from Hillary Clinton, the US secretary of state.
She told delegates Iran was "flouting the rules" of the nonproliferation treaty with its suspect uranium enrichment programme.
"I hope that we can reach agreement in the Security Council on tough new sanctions," Clinton told reporters.
"I believe that is the only way to catch Iran's attention."
The NPT is formally reviewed every five years at a meeting of all 189 treaty members - all the world's nations except India, Pakistan, Israel and North Korea, all of which either have confirmed or are believed to have nuclear weapons.
Tehran has refused to abandon its enrichment programme and now faces the prospect of UN-backed sanctions as a result of its defiance in the face of international pressure.
Ban Ki-moon, the UN secretary-general, said over the weekend that more progress needs to be made in disarmament efforts.
Those efforts have been boosted by new pledges from the US and Russia in recent months.
Ban also said Iran's and North Korea's nuclear programmes were "of serious concern to global efforts to curb nuclear proliferation".