The United States voiced concern on Tuesday after a court in key Gulf ally Bahrain banned the country's main opposition movement just weeks before a parliamentary election.
"Such a move runs contrary to fostering an environment of political inclusion," State Department spokeswoman Jen Psaki told reporters in Washington.
The wealthy Gulf monarchy of Bahrain is home to the US Navy's Fifth Fleet and the country is a member of the US-led coalition being formed to oppose the Islamic State jihadist group.
Washington has been cautious about offending its friend, but has expressed concern over the repression of political dissent in a country with tensions between a Shiite majority and Sunni ruling elite.
On Tuesday, a Bahraini court banned the Al-Wefaq opposition group for three months.
Asked about the decision, Psaki said: "We are concerned by today's decision of the administrative court in Bahrain to suspend the activities of al-Wefaq National Islamic Society for three months on technical grounds."
Political parties are banned in Bahrain, but Al-Wefaq has the status of an association.
The court ruled that the group had violated the rules governing such associations, and gave the group three months to elect new leadership.
Al-Wefaq led a protest movement against the Sunni government and made slender gains in the 2010 election. It withdrew the group's 18 MPs after the government crushed the demonstrations in March 2011.
Awkwardly however, the court decision came as US special envoy, General John Allen, was meeting Bahraini leaders in Manama for talks on building the coalition to fight Islamic militants.
Psaki acknowledged that the US had differences with Bahrain over human rights.
But she added Washington was "grateful for Bahrain's leadership in bringing the coalition together" adding Allen had thanked the Gulf kingdom's leaders for their "participation in coalition airstrikes in Syria."
Psaki also criticized the decision by other opposition groups not to take part in the November 22 elections saying the US wanted to see a "broad participation."