UNITED NATIONS: The United Nations voiced concern Monday after the United States imposed unusually harsh restrictions on the movements of Iran's foreign minister, who was visiting the world body and also speaking on the soaring tensions between the countries.

Weeks after the United States threatened sanctions against Zarif, Secretary of State Mike Pompeo said that Washington issued him a visa but forbade him from moving beyond six blocks of Iran's UN mission in Midtown Manhattan.

"US diplomats don't roam around Tehran, so we don't see any reason for Iranian diplomats to roam freely around New York City, either," Pompeo told The Washington Post.

"Foreign Minister Zarif, he uses the freedoms of the United States to come here and spread malign propaganda," he said.

UN spokesman Farhan Haq told reporters that the UN Secretariat was in contact with the US and Iranian missions about Zarif's travel restrictions and "has conveyed its concerns to the host country."

The United States, as host of the United Nations, has an agreement to issue visas promptly to foreign diplomats on UN business and only rarely declines.

Washington generally bars diplomats of hostile nations from traveling outside a 40-kilometer (25-mile) radius of New York's Columbus Circle.

Zarif is scheduled to speak Wednesday at the UN Economic and Social Council, which is holding a high-level meeting on sustainable development.

Even from the confines of the mission, Zarif -- a US-educated academic who speaks fluent English sprinkled with self-effacing humor -- sought to take his message to the media, as is his wont on UN trips.

The Iranian mission tweeted photos of Zarif speaking to NBC News as well as the BBC.

Despite the restrictions, the decision to admit Zarif is the latest sign that President Donald Trump's administration appears to be retreating from its vow to place sanctions on Zarif as part of its "maximum pressure" campaign on Iran.

Treasury Secretary Steven Mnuchin said on June 24 that sanctions against Zarif would come later that week.

Critics questioned the legal rationale for targeting Zarif and noted that sanctions would all but end the possibility of dialogue -- which Trump has said is his goal.

Zarif said in an interview with The New York Times he would not be affected by sanctions as he owns no assets outside of Iran.

Trump last year left a denuclearization accord negotiated by Zarif with six nations including the United States under former president Barack Obama and instead imposed crippling sanctions on Tehran's economy, vowing to curb Tehran's regional role.

With tensions escalating, Trump ordered military strikes on Iran last month after it shot down a US spy drone, although he canceled the operation at the 11th hour, saying it would be disproportionate.

No US diplomats are based in Iran as the two countries broke off relations in the aftermath of the 1979 Islamic revolution that toppled the Western-oriented shah.