LONDON — Iran’s foreign minister, Mohammad Javad Zarif, offered his congratulations to Boris Johnson on Tuesday after he won a party vote that cleared the way for him to become Britain’s new prime minister, but he also warned the leader-in-waiting that Tehran would protect itself.
The comments came four days after Iran seized a British tanker in the Strait of Hormuz, a vital waterway linking the Persian Gulf and Gulf of Oman. The episode has further ratcheted up tensions between Tehran and the West and revealed the extent to which Britain is directly involved in the conflict.
“Iran does not seek confrontation,” Mr. Zarif wrote in a post on Twitter. “But we have 1500 miles of Persian Gulf coastline. These are our waters & we will protect them.”
Britain angered Iran earlier this month, when its Navy seized an Iranian vessel near Gibraltar alleging it could be in violation of a European Union embargo on the sale of oil to Syria. The move brought warnings of retaliation from Iran, even after British officials tried to calm the situation, that were soon realized.
Mr. Zarif’s sentiments echoed those he made a day earlier during a visit to Nicaragua, when he told reporters that Tehran was trying to avoid conflict despite the seizure of the British vessel. “Starting a conflict is easy; ending it would be impossible,” Mr. Zarif said, according to the Iranian state news outlet Fars.
He also spoke directly about Mr. Johnson, who as recently as last July was the British foreign minister. “It’s important for everybody to realize, it’s important for Boris Johnson to understand, that Iran does not seek confrontation,” he said.
Mr. Johnson is set to take office at a time when the tensions between Britain and Iran are especially high, following on from President Trump’s decision last year to pull the United States out of the 2015 nuclear agreement with world powers and Iran.
The agreement promised Iran relief from economic sanctions in exchange for limits on Tehran’s nuclear program, but tensions have risen ever since the Trump administration introduced punishing new sanctions on Iran in May.
Tehran set a deadline for the deal’s European signatories, including Britain, to come up with a strategy to ease their impact. When that deadline passed, Iran began to reduce its compliance with the accord.
The remaining European signatories to the nuclear deal and Iran will meet in Vienna on Sunday in a bid to save the current agreement amid the backdrop of the increasing tensions in the Persian Gulf and surrounding area, a major conduit for the world’s crude oil supply.
Iran called the seizure of the ship off Gibraltar “piracy” and accused Britain of acting on Washington’s wishes, before threatening to capture a British ship in retaliation. Mr. Hunt, the British foreign secretary, called Iran’s seizure last week of the British vessel a “tit for tat.”
Mr. Hunt, the runner-up in the race to replace Theresa May as prime minister, said on Monday that Britain would be working with European nations to create a protection unit to defend ships passing through the area, and called the seizure of the British vessel “state piracy.”
“When it comes to freedom of navigation, there can be no compromise,” he said, speaking to Parliament, before proposing a “much broader alliance of countries” to provide security to commercial vessels in the region.
Mr. Hunt also sought to distance his country from the tensions between the United States and Iran over the 2015 nuclear deal, noting that Britain “will not be part of the U.S. maximum pressure policy on Iran.”
The dispute over the seized tankers was the latest in a series of back-and-forth episodes between Iran and the West.
Six tankers were damaged in the Gulf of Oman in May and June — incidents that American officials attributed to Iran, and that Tehran has denied.
Last month, Iranian forces shot down an American surveillance drone, an action that prompted retaliatory military strikes from the United States that were called off at the last minute. Then, last week, the United States said it had downed an Iranian drone, which Iranian officials also emphatically denied.
Iran announced on Monday that it had arrested 17 Iranian citizens on charges of spying for the United States. The United States denied those reports, with President Trump saying there was “zero truth.”