ISTANBUL — Turkey’s deputy prime minister apologized on Tuesday for the “excessive violence” used by the police last week against demonstrators opposing the razing of an Istanbul park, the start of what later became nationwide protests against the pro-Islamic government.

The deputy, Bulent Arinc, speaking at a news conference broadcast live from Ankara, appeared to be trying to ease mounting criticism after Prime Minister Recep Tayyip Erdogan on Monday referred to the thousands who have been protesting in 67 cities for at least five days as extremists led by the main opposition party.

“It is wrong, unjust that excessive violence was used against those that acted upon their environmental sensitivities in the initial event,” said Mr. Arinc, referring to the protest in Taksim Square on Friday, which ignited the widespread riots. “I apologize to those citizens.”

In Geneva, the United Nations human rights office expressed concern over the use of excessive force and called for an investigation into possible violations of international human rights standards.