WASHINGTON — The White House said Wednesday it was "deeply concerned" over an upsurge in violence in Bahrain, condemning attacks on police but also calling on security forces to show restraint.

"The United States continues to be deeply concerned about the situation in Bahrain, and we urge all parties to reject violence in all its forms," White House spokesman Jay Carney said in a statement.

The United States has deep and longstanding security ties with the Gulf kingdom, which is headquarters to its Fifth Fleet, but has repeatedly expressed disquiet over the security situation there over the last year.

"We condemn the violence directed against police and government institutions, including recent incidents that have resulted in serious injuries to police officers," Carney said.

"We also call on the police to exercise maximum restraint, and condemn the use of excessive force and indiscriminate use of tear gas against protesters, which has resulted in civilian casualties."

In the latest violence, Bahrainis wielding knives and sticks attacked Shiite villagers overnight as pressure grew for this month's Formula One race in the Sunni-ruled state to be cancelled over the unrest.

On Tuesday, a gasoline pipe bomb injured seven policemen, amid high tensions over the health of Shiite activist Abdulhadi al-Khawaja, who has been jailed for life for plotting to overthrow Sunni King Hamad last year.

Carney expressed "continued concern" for the well being of Khawaja and called on the government to consider all options available to resolve his case.

Mass demonstrations rocked the kingdom last year and were violently crushed as government forces used live ammunition and heavy-handed tactics to scatter protesters.

A special independent commission, called for by the king and backed by Washington, found that police used "excessive force" and tortured detainees in the crackdown.

Carney on Wednesday called on the Bahraini government to "redouble its ongoing efforts to implement the recommendations" of the probe and for all parties to hold a dialogue leading to meaningful political reforms.