Four commercial vessels were targeted by "sabotage operations" near the territorial waters of the United Arab Emirates without causing casualties, the foreign ministry said on Sunday in a statement tweeted by state news agency WAM.
The incident occurred near the UAE emirate of Fujairah, one of the world's largest bunkering hubs that lies just outside the Strait of Hormuz, it said. The strait is a vital oil and natural gas corridor for the global energy market.
"Subjecting commercial vessels to sabotage operations and threatening the lives of their crew is considered a dangerous development," the statement said.
Tensions are running high in the region after the U.S. military sent forces, including an aircraft carrier, to the Middle East to counter what the White House says are "clear indications" of threats from Iran to its forces there.
The ministry gave no details about the nature of the sabotage and said it had launched an investigation in coordination with international authorities. It said the incident did not result in any spills.
The government of Fujairah earlier in a tweet denied media reports about blasts inside the port of Fujairah and said the facility was operating normally.
The statement did not identify the media outlets that published those reports but the Iranian Press TV website cited a Lebanese broadcaster, Mayadeen, saying seven oil tankers were attacked in the port.