WASHINGTON (Reuters) - The Pentagon said on Monday it was unconcerned by an Iranian announcement that it would send naval vessels toward U.S. maritime borders, noting that lots of countries operated in international waters in the Atlantic.

An Iranian naval officer was quoted by the semi-official Fars news agency as saying on Saturday that the vessels were "approaching the United States' maritime borders."

The Pentagon has no information the ships are approaching the Atlantic yet, spokesman Colonel Steve Warren said, adding that "to our knowledge, this is an announcement only at this point."

"We are not concerned about their announcement to send ships into the Atlantic. As I said earlier, freedom of the seas applies to every nation," Warren said.

He said if Iranian ships do head into the Atlantic, "they should not be surprised to find many other navies also sailing in the Atlantic."

Fars said the plan was part of "Iran's response to Washington's beefed up naval presence in the Persian Gulf."

The United States and its allies regularly stage naval exercises in the Gulf, saying they want to ensure freedom of navigation in the waterway through which 40 percent of the world's seaborne oil exports passes.

U.S. military facilities in the region include a base for its Fifth Fleet in the Gulf Arab kingdom of Bahrain.

Iran sees the Gulf as its own backyard and believes it has a legitimate interest in expanding its influence there.

Iranian officials have often said Iran could block the Strait of Hormuz, at the mouth of the Gulf, if it came under military attack over its disputed nuclear program, and the Western war games are seen in the region as an attempt to deter any such move.

(Reporting by Phil Stewart; additional reporting by William Maclean in Dubai; Editing by Mohammad Zargham)