The Post quoted police spokesman Agus Rianto as saying that supporters of the notorious IS movement, which is outlawed in Indonesia, were initially planning to hold a gathering in the province's capital of Semarang, before he talked them out of this.
"A group of people promoted the gathering at a mosque by putting up posters that depicted the IS flag, but we have met with them and they have agreed to cancel it," the police official told reporters.
The poster, which also featured Osama bin Laden, invited people to join a discussion on jihadism and the issue of defending the "caliphate", something that the IS is known to be aspiring to build in the lands of Syria and Iraq.
Meanwhile, Indonesia's terrorist experts have called on the government to remain vigilant, as the movement has reportedly succeeded in drawing over 500 Indonesians under its banners.
Islamic State is a Sunni jihadist group, known for its violent tactics. The majority of Muslims in Indonesia also follow the Sunni tradition of Islam.
IS militants have proclaimed the territories under their control an Islamic caliphate and forced thousands of people, mostly religious minorities, to flee their homes.