TEHRAN, Iran (AP) — Iran's foreign minister on Monday lambasted recent U.S. financial sanctions against him, calling the move a "failure" for diplomacy amid escalating tensions in the Persian Gulf.

"Imposing sanctions against a foreign minister means failure" for any efforts at negotiations, Mohammad Javad Zarif told reporters at a press conference in Tehran, adding that it also means the side imposing the measures is "opposing talks."

The U.S. administration last week announced sanctions on Zarif, a month after President Donald Trump had imposed similar sanctions on Iran's supreme leader, Ayatollah Ali Khamenei.

The moves are seen as part of Washington's escalating campaign in what Trump calls "maximum pressure" on the Islamic Republic.

The U.S. has increasingly deployed military reinforcements to the region amid unspecified threats from Iran in the wake of Trump's withdrawal last year from the 2015 nuclear deal between Iran and world powers.

Zarif stressed that while there are no problems between the American and the Iranian people, Washington's policy of threatening war and "talking about war as an option that remains on the table cannot stand."

Zarif's press conference came a day after Iran announced its forces had seized a foreign ship in the Persian Gulf suspected of carrying smuggled fuel. It was the Revolutionary Guard's third seizure of a vessel in recent weeks and the latest show of strength by the paramilitary force amid the spike in tensions.

Iranian media reported that seven crew members were detained when the ship was seized last Wednesday with "smuggled fuel" from Iran but provided no details on the vessel or the nationality of the crew.

Tensions in the region escalated recently, with the United States boosting its military presence and six oil tankers targeted in the Gulf of Oman in unclaimed acts of sabotage that the U.S. blames on Iran. Iran has denied any involvement in those attacks.

In June, Iran shot down an American surveillance drone in the Strait of Hormuz. Trump came close to retaliating, but called off an airstrike at the last moment. Washington has since claimed that a U.S. warship downed an Iranian drone in the strait. Iran denies losing any aircraft in the area.

Maritime security in the region was further jolted in mid-July, when the Revolutionary Guard's naval forces confirmed they had seized a United Arab Emirates-based oil tanker, the Panamanian-flagged MT Riah, for allegedly smuggling fuel from Iranian smugglers to foreign customers.

Also in July, the Guard seized a British-flagged vessel near the Persian Gulf in the Strait of Hormuz, in what some Iranian officials suggested was retaliation for the seizure of an Iranian oil tanker in a British Royal Navy operation off Gibraltar, near Spain.

Also, Iran recently began surpassing uranium enrichment limits set in the 2015 nuclear deal, but says these moves can be reversed if given enough economic incentives to offset U.S. sanctions.

Referring to the seizure of the British tanker, Zarif said Monday that it was not a reciprocal action for Gibraltar. He also told reporters he had received an invitation from Washington for a meeting during his New York trip in July, along with a warning about the sanctions.

"During my trip to New York, I was told I would be sanctioned within two weeks unless I accept their invitation, which I rejected," Zarif said.

U.S. officials have not confirmed either of Zarif's claims — neither the one about him being warned about the sanctions nor the one about the alleged invitation for talks.