Most of those killed were soldiers. 35 others were injured after militants struck police and military targets.
Bishop Angaelos, the head of the UK's Coptic Orthodox Church has denounced the attack, speaking on Premier's News Hour, he said: "We think about numbers, of 27. These are 27 people who have families, who have communities; to take their lives so tragically as well is a crime in every sense of the word."
On Thursday in Cairo clashes between police and demonstrators led to at least 15 people being killed.
According to Reuters, the return of stability to Arab world's largest country has been impeded in part by the Sinai-based Islamist insurgency that has intensified since the army ousted elected president Mohamed Mursi of the Muslim Brotherhood in mid-2013 after mass unrest over his rule.
Hundreds of security force members have been killed since.
The Brotherhood denies links to the insurgents but the government makes no distinction between the two groups.
"All of us are in sorrow over what happened yesterday in Sinai but Egypt is paying the price of confronting terrorism and extremism," Sisi said in a statement carried by the state news agency MENA.
The most active group, Ansar Bayt al-Maqdis, changed its name to Sinai Province last year when it swore allegiance to Islamic State, the ultra-radical Sunni militant group that has seized swathes of Iraq and Syria, drawing U.S.-led air strikes.
A daily news broadcast released via Islamic State Twitter feeds said Thursday's attacks had been led by "men of the Islamic State".
Bishop Angaelos: