A foreign ministry spokesman told journalists on Sunday the decision to bar them reflected Tehran's anger at an "insulting" resolution on its nuclear activities.
Hamid Reza Asefi added: "We won't allow them to talk to us in such a way. When and how a new date is set, I do not know." 

US officials described the inspections ban as "very worrying".

But International Atomic Energy Agency (IAEA) chief Muhammad al-Baradai said he was confident Iran would reverse its decision to block IAEA inspectors from visiting the country.
Point of view

Asefi claimed the UN resolution at the agency's Vienna headquarters on Saturday "did not take into account the realities".
Iran feels the resolution focused too heavily on omissions and failures in Iran's communications with the IAEA.

"We won't allow them to talk to us in such a way. When and how a new date is set, I do not know" 

Hamid Reza Asefi,
Foreign ministry spokesman

It also failed to highlight its signature of a protocol in December allowing snap inspections of nuclear facilities and its decision temporarily to suspend uranium enrichment.
"The reality should be reflected [in the resolution]. If not, the manner of our cooperation may change. Stopping the inspectors from visiting Iran should be evaluated in that framework," Asefi said.
Resolution detail

In the resolution, the IAEA board said it "deplores" Iran's omissions of key atomic technology from an October declaration, including undeclared research on advanced P2 centrifuges that can make bomb-grade uranium.
It said the board of governors would decide in June how to respond to the omissions - a clause that several diplomats said kept the door open for a possible report to the UN Security Council and economic sanctions.
But Asefi insisted Iran was hiding nothing from inspectors and did not fear being referred to the UN Security Council.
"We're not worried that our case will be sent to Security Council.

"In the first place, we have had good and clear cooperation with the agency and, secondly, we have told them about everything and not hidden anything from them."