The Afghan government plans to announce a second cease-fire with the Taliban during a major Muslim holiday in August as part of an effort to kick-start peace talks involving the U.S., the Islamist insurgency and the government, Afghan and U.S. officials working on the process said.

The Taliban have long said the U.S. is responsible for the hostilities and should be the main negotiating partner. For years, the U.S. has insisted any process should be strictly between the Afghan government and the insurgents.

That...