Iran's parliament speaker, Ali Larijani, said the attack was "planned and carried out from inside Pakistan", saying the country should answer for it. Larijani's remarks were carried by the state-run IRNA news agency on Sunday.
The attack was claimed by Jaish al-Adl [Army of Justice], a jihadist group based in the province.
Saudi Arabia vowed to "de-escalate" rising tensions between Pakistan and India during a high-profile summit in Islamabad on Monday as Crown Prince Mohammed bin Salman prepares to travel from Islamabad to New Delhi.
Iran's strongly worded message to Pakistan comes a day after India's External Affairs Minister Sushma Swaraj met with Iran's Deputy Foreign Minister for Political Affairs Seyyed Abbas Araqchi during a stopover visit in Tehran.
"Iran expects the Pakistani government and army to take necessary measures... against active terror groups in the Pakistani areas bordering Iran", Qassemi said, as quoted by the Telegram channel of the Iranian Foreign Ministry.
The relations between Pakistan and Iran have taken a nosedive following one of the worst attacks on Iranian forces in a restive southeastern region connecting the neighboring Muslim countries.
Wednesday's attack, claimed by Baluch separatists, killed both seasoned officers and younger soldiers, including a 20-year-old in the Isfahan-based Guard's forces.
Replying to a question, he said terrorism is a common enemy and Pakistan, Saudi Arabia and US are working jointly to eradicate this menace.
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Pakistan, Saudi Arabia and the UAE deny backing such militants.
Pakistan's Foreign Office issued no statement on the conversation.
Islamabad has also pledged to act if Tehran shares evidence against those linked to the killing of Iranian guards.
He further stressed that the Pakistani government is responsible for ensuring the safe return of the abducted Iranian border guards.
In September, the Revolutionary Guard said it dismantled a "terrorist cell" and killed four fighters in Saravan, another city in Sistan-Baluchestan province. The Taliban in a release said at the "formal invitation of the government of Pakistan" meeting was scheduled to take place "between the negotiation teams of the Islamic Emirate and the United States on 18th of February 2019 in Islamabad".