The Council of Islamic Ideology (CII) in a "code of conduct" issued for all sects of Muslims also demanded a ban on religious hate speech which often results in violence.
"It is an un-Islamic and condemnable act to declare any Muslim sect a disbeliever and liable to death," it said.
The body also declared that terrorism and violence in the name of religion are a violation of basic Islamic teachings, calling upon all Muslim sects to denounce all such acts.
Tahir Ashrafi, chief of the group, said that they would work with different sects to maintain peace and harmony.
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The group also condemned violence in all forms.
"Islam is religion of peace and there is no room for any kind of violence in our religion. It is important that all groups remain peaceful," the group said.
The Islamic lunar month of Muharram begins on October 24 when Shia Muslims observe the Ashura festival.
Shias take out processions and rallies in the month, which are sometimes attacked by extremist Sunni groups like Lashkar-e-Jhangvi, which is also linked with the Taliban and al-Qaeda.