Qatar sharply condemned the targeting of one of its commercial ships by a drone in the Gulf on Sunday morning.
It was the latest such strike in recent days, which have seen Iran and the US escalate attacks amid an ongoing standoff over the closure of the Strait of Hormuz .
The latest strike caused a small fire on the cargo ship, which was travelling to Qatar's Mesaieed port from Abu Dhabi.
"This attack is a flagrant violation of the principle of freedom of navigation … and a dangerous and unacceptable escalation that threatens the security and safety of commercial sea lanes," Qatar's foreign ministry said in a statement.
The UK's Maritime Trade Operations agency said earlier on Sunday that a cargo ship had been struck by an unidentified projectile while sailing 23 nautical miles northeast of Doha.
This came hours after a Qatari gas tanker appeared to transit the Strait of Hormuz for the first time since the Iran war began.
Tracking data collected by Bloomberg showed the Al Kharaityat exited the waterway en route to Pakistan on Sunday morning.
The ship, which was transporting liquefied natural gas from the Ras Laffan export plant, appears to have transited via the corridor controlled by Iran's Revolutionary Guards, close to the Iranian mainland.
Sources told Reuters that Iran had allowed the shipment through as a gesture to Qatar and Pakistan, which are facing an urgent gas shortage caused by the strait's closure.
A Panama-flagged bulk carrier bound for Brazil also passed through the strait on Sunday.
Qatar's Prime Minister Mohammed bin Abdulrahman al-Thani told Iran's foreign minister in a phone call that using the waterway "a pressure tool" would only intensify the crisis in the Gulf, the Qatari foreign ministry said on Sunday.
This came shortly after Al-Thani met with senior American officials in the US, including Vice President JD Vance , Secretary of State Marco Rubio, and White House envoy Steve Witkoff.
Qatari officials have been working behind the scenes to mediate a peace deal between Iran and the US and end the crisis in the strait.
US officials told Axios that the Qataris had been "especially effective in negotiations in Iran".
Iranian media reported Sunday afternoon that Tehran had submitted its response to the latest US peace proposal, though it did not provide details about its contents.
The two countries have engaged in a standoff over the crucial shipping corridor, which has been largely closed since the US and Israel launched the war 10 weeks ago.
Iran has insisted it should retain control over the strait as part of a peace settlement and wants to impose transit fees on ships to generate billions of dollars of revenues.
The closure has triggered a severe global energy crisis and provoked a US blockade on Iran's ports that it has refused to lift until Tehran agrees to a peace deal.