The terror group said foreign forces would be excluded from the ceasefire and that operations against them would continue. They also said they would defend themselves against any attack.
Afghan President Ashraf Ghani announced an unconditional ceasefire with the Taliban on Thursday, coinciding with the end of the Muslim fasting month of Ramadan, but excluding other terror groups, such as ISIS.
Ghani's decision came after a meeting of Islamic clerics declared a fatwa, or ruling, against suicide bombings, one of which, claimed by ISIS, killed 14 people at the entrance to the clerics' peace tent in Kabul.
The clerics also recommended a ceasefire with the Taliban, who are seeking to reimpose strict Islamic law after their ouster in 2001, and Ghani endorsed the recommendation, saying it would last until June 20.
Ghani has urged ceasefires with the Taliban before, but this was the first unconditional offer since he was elected in 2014.
In August, U.S. President Donald Trump unveiled a more hawkish military approach to Afghanistan, including a surge in air strikes, aimed at forcing the Taliban to the negotiating table.
Afghan security forces say the impact has been significant, but the Taliban roam huge swaths of the country and, with foreign troop levels of about 15,600, down from 140,000 in 2014, there appears little hope of outright victory.