KABUL—A Taliban attack on a govt intelligence headquarters in northern Afghanistan killed 11 stability forces and hurt dozens of civilians, additional straining a peace procedure intended to pave the way for a withdrawal of American troops.

The militants detonated a motor vehicle bomb Monday morning in the city of Aybak in Samangan province outside the house a base belonging to the National Directorate of Security, Afghanistan’s spy agency. Next the blast, two insurgents entered the compound and exchanged hearth with stability forces, in accordance…