The group said that it collaborated with Lashkar-e-Jhangvi, which has been behind numerous bloody attacks on Shiite Muslims in Pakistan.
At least 20 people were killed and 48 others injured in a blast that targeted members of the ethnic Hazara community at a market in Pakistan's Quetta city on Friday, police said.
Balochistan Police Chief Mohsin Butt said that eight Hazara were among the victims.
At least 30 people were injured in the blast in the southwestern city of Quetta, capital of resource-rich Balochistan province, officials said.
Security officials confirmed that the incident took place earlier today in a market in the city.
In Quetta attack, the suicide bomber blew himself up in the midst of Hazara community members who loading their vehicles.
The Pakistani officials have repeatedly denied presence of the ISIS in the country, but the Middle Eastern terror group has claimed a number of attacks in the past.
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He initially said that the explosive device was hidden between sacks of potatoes, but, later, he and the provincial home minister, Zia Langove, told a news conference that a suicide bomber exploded his device among the people in the market.
Shi'ites come to the market at regular times and as a group, with a security escort from police and paramilitary forces.
Members of the Hazara community continued their sit-in for a third day on Sunday at Quetta's Western Bypass to demand better security measures following a blast in Hazarganji market.
The community has been frequently targeted by extremists from Pakistan's Sunni Muslim majority. On Friday, the same practice was followed but the blast took place inside.
Pakistani Prime Minister Imran Khan and President Arif Alvi issued statements condemning the attack and adding that it would not weaken "the resolve of the nation in the fight against terrorism". "Those commitments must translate now into policies to effectively protect the Hazaras of Quetta, ending more than a decade of bloodshed".
Hazaras make up a significant minority group in Pakistan and majority live in Quetta.