Pakistan has lodged a protest with Iran over the killing of six paramilitary troops who were ambushed by militants while patrolling the border.
The Foreign Ministry says it summoned Iran's ambassador to demand it take action against the armed group responsible for the attack.
No one has claimed the attack, and neither country has identified those responsible.
Some 30 militants attacked the Frontier Corps convoy on Friday, killing six soldiers and wounding 14.
Four attackers were killed in the shootout.
Iran condemned the attack Saturday and vowed to cooperate with Pakistan.
A number of militant groups as well as drug smugglers operate in the border region.
Militants captured around a dozen Iranian border guards near the border in October.
Five were released in Pakistan last month, under unclear circumstances.