UN leader Ban Ki-moon said Thursday that Bahrain's move to ban protests could "aggravate" tensions in the Gulf state.
The United Nations joined leading nations in urging a rethink by the Bahrain authorities.
The UN secretary general "expresses his concern about the restrictions" on demonstrations and public gatherings declared on Tuesday, said his spokesman Martin Nesirky.
Bahrain should "abide fully by international human rights standards, including respect for freedom of expression and peaceful assembly and association," the spokesman added.
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"The secretary general believes these restrictions could aggravate the situation in the country and urges the government of Bahrain to lift them without delay."
Bahrain banned all protests and gatherings to ensure "security is maintained," after clashes between Shiite-led demonstrators and security forces in the Sunni-ruled country.
The Gulf state has experienced unrest since March last year when authorities crushed protests led by the Shiite Muslim majority demanding greater rights.
Ban also said protesters should ensure that demonstrations are peaceful. "Recent violence that reportedly killed two police officers is unacceptable."
On Wednesday the United States said it was "deeply concerned" at the protest ban.
"We urge the government of Bahrain to work with responsible protest leaders to find a way for peaceful and orderly demonstrations to take place," said US State Department spokesman Mark Toner.