Iranian Foreign Minister Javad Zarif's recent travel to New York for a U.N. sustainable development forum was marked by severe restrictions on his movements and sparring in the press with U.S. officials.

Already high tensions between the two countries spiked on July 18, the last day of the forum's ministerial meetings, when Washington said it had destroyed an unmanned Iranian drone over the Strait of Hormuz. President Donald Trump claimed the strike was "defensive" and accused the Middle Eastern country of "many provocative and hostile actions."

Iran, for its part, denied having lost a drone. Zarif said there was "no information" about any such strike, while Deputy Foreign Minister Abbas Araghchi tweeted wryly that he was "worried" the United States may have accidentally shot down its own aircraft.

Just prior to the arrival of Zarif -- a U.S.-educated diplomat who was instrumental in the 2015 nuclear deal between Iran and six world powers -- the United States tightened its restrictions over Iranian officials and their families, limiting their movements to a six-block radius around U.N. headquarters in Manhattan.

That means Iranian diplomats and their families are not allowed to walk around Central Park or visit most of the key sightseeing spots in New York such as Times Square or the Statue of Liberty.

Speaking to reporters at the international body, Zarif said the new rules did not inconvenience him personally during his brief visit, but voiced concern over the "basically inhuman conditions" for Iranian diplomats and their families living in New York.

The U.N. secretariat, according to spokesman Farhan Haq, has also "conveyed its concerns to the host country" over the arrangements. They are far more severe than the 25-mile radius for movement that still applies to diplomats from North Korea, Syria and Cuba, who can thus move freely in Manhattan and some suburban areas of New York.

"U.S. diplomats don't roam around Tehran, so we don't see any reason for Iranian diplomats to roam freely around New York City," Secretary of State Mike Pompeo was quoted as saying by The Washington Post.

Bilateral relations have deteriorated since Trump's 2018 withdrawal of the United States from the nuclear deal negotiated under his predecessor Barack Obama. Under the accord, Tehran agreed to curb its nuclear activity in exchange for the lifting of sanctions.

Since the U.S. withdrawal and re-imposition of unilateral sanctions, there has been more pressure on the five other countries remaining in the deal -- Britain, China, France, Germany and Russia -- to negotiate with Iran on a way forward. Tehran has reduced its compliance with the accord by exceeding nuclear enrichment limits, while saying its actions could be reversible if progress is made toward providing economic benefits and stability to Iran.

During the high-level meeting at U.N. headquarters, Zarif characterized the sanctions faced by his country as "the most brutal form of economic terrorism, deliberately targeting innocent civilians to achieve illegitimate political objectives."

Tensions over military activities ratcheted up in late June after Iran's Islamic Revolutionary Guard Corps downed an unmanned U.S. drone in the southern province of Hormozgan facing the Persian Gulf.

Zarif and other Iranian officials insisted that the drone had entered Iranian airspace, while Trump claimed it was "clearly over international waters" and said Iran "made a big mistake."

Other flare-ups with the West have occurred this month, beginning with the seizure of an Iranian oil tanker, thought to be heading to Syria, by Gibraltar authorities in support of British Royal Marines.

Possibly in retaliation, Iran seized a British-flagged tanker in the Strait of Hormuz on July 20. For a short period the same day, it also detained a Liberian-flagged vessel owned and operated by a Glasgow firm.

[Gallo Images/Getty/Kyodo]

Iranian state media later aired footage purporting to show some of the 23 crew members of the British-flagged Stena Impero, which is still being held in southern Iran.

Britain's then foreign secretary, Jeremy Hunt, denounced Iran for what he called an act of "state piracy." Tehran has maintained that the British vessel violated maritime laws in the region.

No sign of reconciliation seems in sight yet between the United States and Iran.

"We will never start a war," Zarif said in an interview with CNN during his travel to New York. "But we will defend ourselves. And anybody who starts a war with Iran will not be the one who ends it."

Trump was equally defiant. "We are ready for the absolute worst," he said. "We're ready for sense, too, but we are very geared-up."