Tehran on Thursday denied a Bahraini claim it had found an Iranian drone in the sea near Saudi Arabia, and urged Manama to refrain from making "baseless accusations", the ISNA news agency reported.
It cited an unnamed foreign ministry source as denying Bahrain's assertion that the downed aircraft was Iranian.
"Instead of making baseless claims, it would be better to respond to the legitimate demands of its people," the source said of the Shiite-majority kingdom across the Gulf that is ruled by a Sunni Muslim dynasty.
On Wednesday, Bahrain government spokeswoman Samira Rajab said the unmanned aircraft "was found in the sea in north Bahrain, mainly between Bahrain and Saudi Arabia, two weeks ago".
"It has been proved that this is a drone used by Iran and could be linked to the Iranian spy cells discovered in Saudi Arabia and Bahrain," she added.
It was unclear if the aircraft had crashed into the sea or was brought down.
The US navy's Fifth Fleet is based in Bahrain, and the Islamic republic, Washington's arch-foe, has fleets of drones which it says can be used for attacks as well as for surveillance.
On Tuesday, Iran's main rival across the Gulf, Saudi Arabia, said its authorities have arrested 10 more suspects in an alleged Iranian spy ring unveiled two months ago. Tehran has denied links to the cell.
Bahraini Interior Minister Sheikh Rashid Al-Khalifa on Wednesday urged "further cooperation and collaboration between security services in the region and with friendly states to face these threats" by Iran.
Sunni Muslim Arab monarchies in the Gulf have long had strained ties with predominantly Shiite Iran.
These deteriorated further in early 2011 after a Saudi-led military intervention crushed Shiite-led pro-democracy protests in Bahrain.