Iran on Tuesday said it regretted Bahrain's move to ban the Sunni-ruled kingdom's opposition groups from having contact with Hezbollah, Lebanon's Shiite militant movement and close ally of Tehran.
"Bahrain's stance towards Hezbollah is regretful," foreign ministry spokesman Abbas Araqchi said at his weekly press conference.
Bahrain on Monday banned opposition groups from all contact with Hezbollah in a bid to limit the movement's perceived influence on its restive Shiite majority.
Last month the Gulf state branded Hezbollah as a "terrorist organisation".
Hezbollah, like Iran, is backing the regime of Syrian President Bashar al-Assad against rebels.
The group has fighters on the ground alongside the Syrian army, in a conflict that has killed more than 94,000 people since it erupted more than two years ago.
Hezbollah fighters are currently engaged in a fierce battle against rebels for control of the central Syrian town of Qusayr.
Araqchi said Hezbollah has an "undeniable" role in ensuring Lebanon's security and stability and accused Bahrain of "deflecting its domestic problems on foreign groups".
Relations between Shiite Iran and the Gulf kingdom, ruled by a minority Sunni dynasty, have been strained since February 2011 when Tehran backed anti-regime protests there which were led by the Shiite political opposition.
Those protests were quelled by security forces that were assisted by Gulf troops led by Saudi Arabia. Iran vociferously condemned the move.
Since then, Bahrain and other Gulf states have repeatedly accused Iran of meddling in their affairs, a charge that the Islamic republic categorically denies.