Iran attacked a Singaporean cargo ship passing through the Strait of Hormuz on Thursday — hours after the regime threatened “violators” who didn’t obey its heavily-controlled routes would be “dealt with.”

The commercial vessel was hit by an explosive drone around 10 a.m. EST as it was passing through a new United Nations-backed route along the Omani coast, sources told The Post.

No casualties were reported; however, the attack tests the fragile deal signed last week by the US and Iran to end the fighting and reopen the vital waterway. The ship sustained damage to its bridge after the strike, sources said.

Just hours before the attack, Tehran warned any ship not following its own sanctioned route through the Strait was “unacceptable and completely dangerous.” 

The new route, devised to allow ships that had been stuck in the Strait for more than 100 days, was agreed upon by the US and Oman on Tuesday — but the defiant regime whined that it was announced without their input.

“Without notice or coordination with the Islamic Republic of Iran, some authorities announced a new route for ship traffic in the Strait of Hormuz,” the hardline Islamic Revolutionary Guard Corp (IRGC) seethed in a statement Thursday morning.

“It is hereby notified to all that the only authorized route for passing through the Strait of Hormuz is the one declared by the Islamic Republic of Iran,” the IRGC added. “Vessel traffic outside these routes is extremely dangerous and prohibited. Violators will be dealt with.”

The Strait of Hormuz — where 20% of the world’s oil supply flows — had officially been reopened since Washington and Tehran signed a memorandum of understanding last week.

However, daily passage has remained a trickle since the deal was signed — far below the pre-war levels of about 135 ships a day. 

About 26 ships passed through the Omani route on Wednesday, compared with just 15 that followed the Iranian route that same day, the Financial Times reported.

Iran began broadcasting warnings about the route Thursday morning, with the IRGC’s statement being accompanied by a Navy broadcast warning ships against using the Omani corridor where the attack later occurred.

In addition to the attack on the Singaporean ship, another four ships were halted and turned around by Iran on Thursday after trying to follow the Omani route, the Times reported.

The International Maritime Organization — the UN group that oversees maritime diplomacy — also halted all activity along the Omani route after the attack, pending further clarification of the situation.

“I have been informed of an attack today in the Gulf of Oman. Seafarer safety remains paramount. To ensure coordinated approach & navigational safety, the IMO evacuation plan will be paused until further clarity,” IMO Sec. General Arsenio Dominguez said in a statement.

The attack could increase tensions between the US and Iran, as the memorandum of understanding to end the war has been on a hair-trigger since being inked.

The deal agreed to cease hostilities for a 60-day period while further negotiations about the likes of nuclear weapons carry on, with Iran agreeing to open the Strait during that time in return for US oil sanctions being lifted.