The Saudi-led coalition fighting in Yemen said Houthi rebels have attacked a Saudi oil tanker, causing "minor damage".
The coalition statement said the attack occurred in international waters on Tuesday near the Red Sea port of Hodeida.
The coalition said a naval ship belonging to a member country rapidly intervened, without giving further details.
Spokesman Colonel Turki al-Malki said a coalition naval ship accompanied the oil tanker until it completed its navigation north.
Col al-Malki described it as a "terrorist attack" that threatens ships entering the vital Bab al-Mandeb strait, used for oil shipments from the Gulf to Europe.
Pictures carried by state-run Saudi al-Ekhbariya TV showed a hole ripped through the side of the ship but no oil leaking out.
The Houthis have in the past targeted military ships belonging to coalition partners Saudi Arabia and the United Arab Emirates, but the attacks have failed to cause any substantial damage.
Tuesday's attack came one day after an air strike by the Saudi-led coalition killed at least 14 people near Hodeida.
The air strike hit a compound housing displaced people in the town of al-Hami. Deputy health minister Walid al-Emmad said at least eight women and five girls were among those killed.
The Saudi-led coalition has been at war with the Iran-allied Houthis for more than three years, a conflict that has killed more than 10,000 Yemenis and devastated the Arab world's poorest country.
Saudi-led air strikes have killed thousands of civilians and destroyed hospitals, schools and markets.
Col al-Malki suggested Iran had a hand in Tuesday's attack, repeating Saudi allegations that Tehran is arming the Houthis.
The US, which is providing some support to the coalition, and its Arab allies accuse Iran of providing increasingly sophisticated weapons to the Shiite rebels, including ballistic missiles fired at the kingdom. Iran denies arming the rebels.
The Houthis have fired close to 100 missiles towards Saudi Arabia since the war began. Last week, a missile attack killed an Egyptian worker and wounded two others in the Saudi capital, Riyadh.
Meanwhile in Geneva, UN Secretary-General Antonio Guterres said a conference had collected pledges of more than two billion US dollars for humanitarian assistance for Yemen.
Saudi Arabia and the UAE pledged one billion US dollars towards the humanitarian response plan.