The US military says it shot down an Iranian drone that “aggressively” approached the Abraham Lincoln aircraft carrier in the Arabian Sea.

The Iranian Shahed-139 drone was flying toward the carrier “with unclear intent” when an F-35 fighter jet shot it down, US Central Command said on Tuesday.

“An F-35C fighter jet from Abraham Lincoln shot down the Iranian drone in self-defence and to protect the aircraft carrier and personnel on board,” Capt Tim Hawkins, a navy spokesperson at Central Command, said. No US service members were harmed or equipment damaged, he said.

The incident came as diplomats attempted to arrange nuclear talks between Iran and the US, and Donald Trump said that with US warships heading toward Iran “bad things” would probably happen unless a deal could be reached.

Iran’s president, Masoud Pezeshkian, said on that Tuesday he had instructed the country’s foreign minister to “pursue fair and equitable negotiations” with the US, the first clear sign Tehran wants to negotiate with Washington.

The announcement marked a significant turn for the reformist president, who had told Iranians for weeks that the turmoil in the country had gone beyond his control. It also indicated that he had the support of Iran’s supreme leader, Ayatollah Ali Khamenei, for talks, which the 86-year-old cleric had previously dismissed.

The Lincoln carrier strike group is the most visible part of a US military buildup in the Middle East after a violent crackdown against anti-government demonstrations in Iran last month, the deadliest domestic unrest since the 1979 revolution.

Trump, who stopped short of carrying out his threat to intervene during the crackdown, has since demanded Tehran make nuclear concessions, and has sent a flotilla to its coast. He said last week Iran was “seriously talking”, while Tehran’s top security official, Ali Larijani, said arrangements for negotiations were under way.

Central Command said that in another incident on Tuesday, in the Strait of Hormuz, Iran’s Revolutionary Guards harassed a US-flagged and crewed merchant vessel.

“Two IRGC boats and an Iranian Mohajer drone approached M/V Stena Imperative at high speeds and threatened to board and seize the tanker,” Hawkins said.