The Supreme Judicial Council, Egypt's highest judicial authority, described President Mohamed Morsi's decision to grant himself new powers putting him above the judiciary as an "unprecedented assault" on the independence of the judiciary.
The new edicts give the president near-absolute power as well as immunity from appeals in courts for any decisions or laws he declares until a new constitution and parliament are in place.
In an emergency meeting on Saturday, the council urged Morsi "to distance this decree from everything that violates the judicial authority".
Al Jazeera said that the Judges' Club has also voiced its anger at the decree.
"With the president giving himself the right to issue decrees or rules that are binding and cannot be appealed, they're saying that never in the history of modern Egypt has there been a president who gave himself so many powers," said Abdel-Hamid.
A Cairo protester's sign read: "Go away Morsi, Egypt is too big for you. People want the fall of the regime"
Morsi's announcement on Thursday sparked large protests across Egypt on Friday, which lasted into the night. On Saturday, demonstrators near Tahrir Square manned makeshift barricades and threw rocks at security forces, who fired back tear gas.
Opponents of the decree have called for a large-scale demonstration on Tuesday. Left wing and liberal parties have called for an open-ended sit-in aimed at "toppling" the decree.
"We are facing a historic moment in which we either complete our revolution or we abandon it to become prey for a group that has put its narrow party interests above the national interest," the liberal Constitution party said in a statement.
Insisting upon the need to root out what he called "weevils eating away at the nation of Egypt," Morsi said on Friday: "I don't like, want or need to resort to exceptional measures, but I will if I see that my people, nation and the revolution of Egypt are in danger."
"I don't want to have all the powers...but if I see my nation in danger, I will do and I will act. I must," said Morsi.
U.S. State Department spokeswoman Victoria Nuland said Morsi's actions raise "concerns" for many Egyptians and the international community, and said the U.S. urged "all Egyptians to resolve their differences over these important issues peacefully and through democratic dialogue".