Bahrain arrested several suspected militants ahead of an attack and seized weapons and explosives that had come from Iran, the interior ministry said on Monday.
The ministry, tweeting the news, did not say how many people were arrested or specify their nationalities. It described them as "linked with terrorist groups in Iran" and said they were "plotting terrorist operations against security and civil peace".
Bahrain, host to the US Navy's Fifth Fleet and other international naval operations, has often accused Shiite Muslim Iran of seeking to subvert the Sunni-ruled kingdom, which has a Shiite majority. Iran has denied such charges.
The island state was the only Gulf Arab state to witness a sizeable pro-democracy uprising in the 2011 "Arab Spring", from a largely Shi'ite opposition movement, which it quashed with help from Saudi Arabia and the United Arab Emirates.
Last year, Bahrain said it had foiled a "terrorist attack" backed by Iran's Islamic Revolutionary Guard Corps.
Iranian officials and government-controlled media routinely attack Bahrain’s royal family and its close ties with Saudi Arabia.