In a 20-minute video called 'Kill all the Kuffar' - translated as 'unbelievers' from Arabic - IS encourages jihadists to kill Egypt's Christians, according to AMN.
It includes footage of the alleged Cairo church bomber named by IS as Abu Abdallah al-Masri.
Egyptian president Abdel Fattah al-Sisi had previously identified 22-year-old student Mahmoud Shafik, who had taken on the new name of al-Masri after he joined the group.
In the video, the jihadist tells IS not to give up.
"Finally, to my brothers in captivity: rejoice, you believers, do not falter or grieve. I swear to God we will very soon liberate Cairo and free you from captivity. We will come bearing explosives, I swear we will, so rejoice you believers," al-Masri said.
Christianity in Egypt
- Population: 95.2 million (9.5 million Christians)
- Open Doors World Watch List Rank: 21
- Source of persecution: Islamic extremism
- Christians in Egypt are often targeted for terror attacks by IS and the Muslim Brotherhood
- Last week, at least two Coptic Christians were murdered
- Christians also face a number of legal barriers when they attempt to construct churches
The church bombing last December was one of the deadliest attacks on Egyptian Christians in recent years.
The suicide bomber detonated the explosive device in the women's section of the church.
One of the victims of the attack was only ten years old.
Coptic Christians make up ten per cent of the population of Egypt.