Iran's government says it will reduce cooperation with United Nations nuclear inspectors in response to new sanctions imposed by the UN Security Council.
Iran insists its nuclear programme is purely peaceful
President Mahmoud Ahmadinejad said separately that the sanctions were illegal and Iran would not stop its nuclear work "even for one second".
The sanctions block Iranian arms exports and freeze assets of anyone involved in nuclear and missile work.
Iran denies seeking nuclear weapons, insisting its work is peaceful.
"After this illegal resolution was passed against Iran last night [Saturday], it forced the government to... suspend parts of its activities with the [International Atomic Energy Agency, IAEA]," government spokesman Gholamhossein Elham said on state television.
"Subsidiary arrangements" with the IAEA would be affected until Iran's nuclear programme was referred back to the IAEA from the Security Council, he said.
This refers to a 2002 agreement by Iran to declare any plans it has to build new atomic-related facilities well in advance, an unnamed senior Iranian nuclear official told Reuters news agency.
IAEA inspectors have been verifying Iran's nuclear programme for the past four years but last month its director-general, Mohamed ElBaradei, reported that their work had been hampered by Iran's failure to "provide the necessary level of transparency and cooperation".
Writing on his presidential website, Mr Ahmadinejad said Iran would "adjust" its ties with those behind the sanctions, without giving details.
"Iran will not stop its peaceful and legal nuclear trend even for one second because of such an illegal resolution," he wrote.
Earlier, the European Union's foreign policy chief said he hoped to resume talks with Iran over its nuclear programme
Javier Solana said he would contact Ali Larijani, Iran's senior negotiator, in an effort to schedule new discussions.