Iran on Monday warned Pakistan that it would hit terrorist safe havens inside that country if the government does not confront militants who carry out cross-border attacks.
The border area has long been plagued by unrest from both drug smuggling gangs and separatist militants.
Major General Mohammad Baqeri, the Chief of Iranian Armed Forces, said the enemies were trying to make up for their failures through hiring terrorists to target Iran's borders or interests. He said the method was that of "cowardly thieves and bandits" and would only bring the enemies "humiliation and ignominy," Press TV reported.
In 2014 Iran warned it would send troops to Pakistan to retrieve five Iranian border guards kidnapped by Jaish al Adl. Pakistan said at the time that such action would be violation of the international law and warned Iranian forces not to cross the border.
Iran refrained from sending the troops when a local Sunni cleric stepped in and resolved the situation.
Four of the guards were released a few months later, but one was killed by the militants.
Jaish al Adl is a Sunni militant group that has carried out several attacks against Iranian security forces with the aim of highlighting what they say is discrimination against minority Sunni Muslims in Iran, where the majority are Shi'ites.
The group claimed responsibility for attacks that killed eight border guards in April 2015 and 14 border guards in October 2013.