Bahrain security forces have arrested a number of suspects, and confiscated weapons and explosives ahead of a planned attack, the interior ministry said.
The ministry did not say how many people were arrested or specify their nationalities.
“Terrorists (were) arrested for plotting terrorist operations against security and civil peace,” the interior ministry wrote on Twitter on Monday.
It described them as “linked with terrorist groups in Iran”.
Bahrain, host to the United States Navy’s Fifth Fleet and other international naval operations, has often accused Shia Muslim Iran of seeking to destabilise the Sunni-ruled kingdom, which has a Shia majority population. Iran has denied such allegations.
The island state was the only Gulf Arab state to witness a sizeable pro-democracy uprising in the 2011 Arab Spring, from a largely Shia opposition movement, which it quashed with help from Saudi Arabia and the United Arab Emirates.
Opposition movements have been outlawed and hundreds of dissidents have been imprisoned – with many stripped of their nationality.
Human rights groups have frequently said cases against activists in Bahrain – men and women, religious and secular – fail to meet the basic standards of fair trials.
Bahrain’s authorities have repeatedly rejected the accusations.
Last year, Bahrain said it had foiled a “terrorist attack” backed by Iran’s Islamic Revolutionary Guard Corps.