Egypt's President Abdel-Fattah El-Sisi and top Egyptian institutions and officials have condemned Friday's terrorist attack on a Helwan church, calling for heightened security and for Muslims to join Christians in their religious celebrations to show unity against terrorism.

El-Sisi praised the "heroic spirit and high sacrifices" of security personnel foiling the terrorist attack, which was aimed at Mar Mina Coptic church in south Cairo.

A statement by El-Sisi's office described the attack as "vicious" and urged heightened security around vital state institutions.

El-Sisi extended his condolences to the families of the martyrs of the terrorist attack, adding that desperate attempts to sow terror will only increase the insistence of Egyptians to continue cleansing the country of terrorism and extremism.

The interior ministry said in a statement on Friday afternoon that police had arrested the attacker who attempted to drive through security forces outside the church armed with a machine gun, ammunition and a bomb that he intended to detonate in the church.

The ministry said he killed two people when he opened fire on a shop, before heading to the church where he shot dead seven people, including a policeman.

The arrested attacker is an active terrorist who has carried out a number of terrorist attacks targeting police and civilians, the statement added.

Egypt's Grand Imam Ahmed El-Tayyeb harshly condemned the terrorist attack, calling on Egyptian Muslims to join Copts in Christmas celebrations, as a form of rejection of the evil plans of terrorists.

El-Tayyeb said in a statement that the aims behind terrorist attacks that target Copts on days of celebration is now exposed, and that foiling these aims by holding onto love and attachment that bring together Muslims and Christians is the most painful response to the terrorists.

Egyptian Grand Mufti Shawky Allam said that those who "attack churches and terrorise the people in them" is "an enemy of the Prophet," adding that what terrorist and extremist groups have done is religiously forbidden and violates the high principles of sharia law, which calls for preserving souls, making the sacredness of innocent blood the same as the sacredness of the holy Kaaba.

The Coptic Orthodox Church spokesperson Boules Halim announced that a collective funeral for the martyrs in the attack will be held at a time and place to be later announced.

The Egyptian cabinet also condemned the Friday attack, extending condolences to the families of the victims, affirming that terror will not shake the determination of the government and the unity of Egyptians fighting in terrorism.

Egypt's parliament also extended condolences to the families of the victims, saying that the "bullets of terrorists did not differentiate between a Muslim and a Christian, or between a mosque and a church," as terrorism targets all from the national social fabric.

Cairo's security chief and a number of security officials visited the scene of the terrorist attack on Friday.

Coptic Christians, who make up around 10 percent of the country's 93 million population, celebrate Christmas on 7 January.

Dozens of Christians have been killed in terrorist attacks on churches and congregations in recent years.

Police have deployed 230,000 personnel to protect churches, parks and other vital public institutions during the Christmas season.