Iran has promised to stop deporting refugees
She said the pause was needed to enable humanitarian agencies to gain access before winter sets in.
Their comments came after the UN refugee agency (UNHCR) warned it was not ready to deal with any mass influx of refugees from Afghanistan.
The UNHCR recently predicted that 1.5 million people might be heading for Afghanistan's borders, but said volatile security around proposed camps in Pakistan and Pakistani bureaucracy meant it had no way of monitoring the actual numbers.
The agency's high commissioner, Ruud Lubbers, said he feared the new camps would not be ready in time for the fast-approaching winter.
Pakistan has difficulty coping with the two million Afghan refugees already on its territory.
A UNHCR spokesman said the Pakistani authorities had apparently not checked with local people before agreeing on the sites of new camps.
"Six sites we surveyed and we thought were viable and where work was about to begin, the government pulled them without an explanation," he said.
"Right now we have five viable sites of which work on one site is under way. We have to have work start on 15 sites as soon as possible to be ready for 150,000 people."
Mr Lubbers said it was a "real race against time" that the UNHCR was losing.
"Compounding the problems is the insistence of the Pakistani Government that any new camps be built in dry, remote and insecure tribal areas along the Afghan border," he said.
Pakistani dilemma
The news comes amid reports that the Pakistani authorities may rethink a ban on the entry of refugees from Afghanistan.
Reuters news agency quoted a Foreign Ministry spokesman as saying that Pakistan had always been generous in caring for refugees and the decision to seal its borders with Afghanistan would be reviewed if necessary.
Border officials are already admitting Afghans in need of medical help.
But the Pakistan administration, plagued by domestic violence and a potential surge in Afghan refugees, has given no guarantees on any opening.
And the government's chief spokesman, Major-General Rashid Qureshi, warned Afghan refugees could be deported if they caused trouble in Pakistan.
He said that about 60% of anti-US demonstrators were Afghan refugees, drawn from the more than two million Pakistan shelters.