U.S. President Barack Obama condemned violence and called for restraint in Bahrain during phone talks with the country's King Hamad bin Isa Al-Khalifa on Friday evening, the White House said in a statement.

Obama reiterated his "condemnation of the violence used against peaceful protesters," and strongly urged the government of Bahrain to "show restraint" and to hold those responsible for the violence accountable, said the statement.

The stability of Bahrain depends upon "a process of meaningful reform that is responsive to the aspirations of all Bahrainis," it added.

Four protesters were killed and dozens wounded after anti-riot police stormed the Pearl Square in central Manama on Thursday.