I would note two things.
The Taliban and the Iranians nearly went to war the late nighties after several "Diplomats" were killed by Talib forces in Western Afghanistan. They were probably military liasons or intelligence officers supporting Ismail Khan's locals but the Iranians did indeed have Diplomatic status.
Radical Balochs in Pakistan and Afghanistan are intent on carving out a Baloch homeland that includes parts of Iran. According to Seymour Hersch we have used them as a proxy to destablize Tehran.
It may very well have come to the point where it is in Irans interest to push back through Talib forces although one shouldn't understimate the Sunni Shia ideological divide between the Iranians the Taliban.
Ironic, especially when the fanatical Shia in Iran hate the fanatical Sunni Taliban and almost went to war with them when they ruled Afghanistan in the late 90's.
Appears I managed to write the same thing while you were posting.