WELLINGTON: Iran's foreign minister on Monday defended the nation's right to use ballistic missiles following a test last week, but offered no explanation for anti-Israeli messages reportedly written on them.

Speaking in Wellington, New Zealand, Mohammad Javad Zarif said Iran has always reserved the right to defend itself.

"Anybody who is crazy enough to attack us, we will attack back using conventional weapons," he said. "We hope that these conventional weapons will never be used because we do believe that in a war, everybody loses."

Zarif was responding to questions following an address to the New Zealand Institute of International Affairs. He'd earlier met with New Zealand Prime Minister John Key to talk about trade, and on Tuesday will travel to Australia.

Last Wednesday's missile test was aimed at demonstrating that Iran will push ahead with its ballistic programme after scaling back its nuclear programme under the deal reached last year with the US and other world powers.

Iran's Fars news agency reported that the missiles had the phrase "Israel must be wiped out" written on them.

Zarif said he hadn't yet returned to Iran to check out those reports. When pressed about the issue, he said it was Israeli Prime Minister Benjamin Netanyahu and U.S. President Barack Obama who were acting aggressively.

"I ask you to go ask Netanyahu why is he threatening to use force against Iran every day. Go ask Obama why he is threatening to use force against Iran every day," Zarif said. "Why are they saying all options are on the table?"

In another development, Zarif ruled out his country accepting the involuntary return of deported Iranians from Australia, dashing Australian hopes of striking a bilateral deal that could send thousands of failed asylum seekers back to their homeland.

Zarif said his government was prepared to cooperate with Australia by encouraging would-be refugees to return home and by giving assurances that they would not be punished. But he drew the line at pressuring them.

"We will not take anybody back to Iran against their will unless they are a criminal and wanted by a court," he said. "They have not committed any crime by trying to go and seek a better life, so they can always come back, but we will not impose on them to come back."

Australian Foreign Minister Julie Bishop had earlier played down prospects of a repatriation deal being struck during Zarif's visit, telling reporters during a trip to Fiji that talks were in a "very early stage."

The asylum seekers have been left with uncertain futures, with Australia refusing to resettle them and Iran refusing to take them back.