A US warship shot down three drones after three commercial vessels came under attack in the Red Sea, the US military has said.
It said the USS Carney assisted the ships - which had links to 14 nations including the UK - on Sunday after they were targeted from areas of Yemen held by Iran-backed Houthi rebels.
Two of the ships were hit by missiles but there were no casualties, it added.
A Houthi spokesman said the group's navy had attacked two Israeli ships.
The Israeli military said the vessels had no connection to Israel.
The Iranian-backed Houthis have controlled parts of Yemen since the movement toppled the country's government in 2014, sparking an ongoing civil war.
It has recently begun targeting Israel-linked vessels in the Red Sea over Israel's war with Iranian-backed Hamas in Gaza.
US Central Command (Centcom), part of the US military which oversees operations in the Middle East, said that on Sunday morning, the USS Carney detected an anti-ship ballistic missile exploding near the Unity Explorer, a Bahamian-flagged, UK-owned and operated cargo ship.
It later shot down a drone that was heading towards the Carney itself, although Centcom said it was not clear whether the drone was targeting the Carney.
That afternoon, the Unity Explorer suffered minor damage after being struck by a missile fired from Houthi-controlled area.
While responding to a distress call from the ship, the US vessel detected and shot down another incoming drone.
Later, two more ships - one of them part UK-owned, both of them flagged in Panama - reported being struck by missiles. While on its way to assist the second ship, the USS Carney shot down a third drone
Centcom said the attacks had "jeopardised the lives" of the ships' multinational crews and represented a "direct threat to international commerce and maritime security".
"We also have every reason to believe that these attacks, while launched by the Houthis in Yemen, are fully enabled by Iran," it said.
"The United States will consider all appropriate responses in full coordination with its international allies and partners."
Earlier this week, the US said its warship captured armed men who had earlier seized an Israeli-linked tanker off Yemen's coast.
Centcom reported that two missiles were then fired towards the warship from rebel Houthi-controlled territory in Yemen.
The Houthis have declared themselves part of an "axis of resistance" of Iran-affiliated groups, which works in opposition to Israel, the US, and the wider West.