An Indian fisherman was killed and three people wounded as their boat was shot at off the coast of Dubai in the southern Gulf.
"The firing has led to the death of one Indian national and serious injury of three Indian nationals," Tarek al-Hedan, an
aide to the foreign minister for political affairs, told the official WAM news agency on Monday.
"The services concerned are now investigating this incident," he said.
Lieutenant Greg Raelson, a spokesman for the US navy's Bahrain-based 5th Fleet, said sailors aboard the USNS Rappahannock opened fire on the boat after it ignored warnings.
"US ships have an inherent right to self defence against potential threats... The safety of our vessels and our personnel is of the utmost priority," he told Al Jazeera in an email response to a query.
The shooting took place at around 2pm local time (10:00GMT) about 16km from the coast, the US navy said.
The Rappahannock - with a crew of 81 civilians and three military officers - was headed into the UAE port of Jebel Ali when the small motor boat came within 8km of it, the navy said.
Navy officials told Al Jazeera the crew first tried to hail the vessel via radio and on loudspeaker, as well as by flashing lights and firing warning shots. They then shot at the boat with a 50 calibre weapon.
Dozens of police and other Emirati officials crowded around the boat after it docked following the incident at a small Dubai port used by fishermen and sailors. The boat was removed from the port shortly afterwards.
Rescue workers were seen carrying one person in a body bag off the white-hulled boat and placing it in an ambulance as fishermen looked on, the Associated Press news agency reported.
The nine-metre long boat was powered by three outboard motors.
Similar boats are used for fishing in the region, though Iran's Revolutionary Guard also employs relatively small, fast-moving craft in the Gulf.