Another human rights lawyer, Ahmed Ragheb, praised Morsi's decree but said it doesn't include "all the victims of the past period."
Ragheb said Morsi's choice of wording in the decree — "those supporting the revolution" — can be interpreted in different ways.
"No one is facing charges called 'supporting the revolution,'" Ragheb said.
Protesters currently on trial face charges ranging from resisting authorities, damaging public or private property or disrupting public order. More than a 12,000 civilians have been brought before military tribunals, many of them on charges such as "thuggery."
It will be up to the prosecutor general and the military prosecutor to name those who will be pardoned. Suspects who are excluded can challenge the decision, and a judicial panel would be the final arbiter.
Seif said it could take months before pardons actually materialize.
A month after becoming president, Morsi pardoned more than 500 civilians convicted before military tribunals.
But rights groups have criticized Morsi, and the military generals who ruled before him, for failing to bring to trial most of the policemen, army troops and officers suspected of using excessive force or torture against protesters.
Mohammed Abdel-Aziz, a lawyer involved in many of the protesters' cases, said the amnesty is too little too late and that the pardons should come with a financial compensation.
Abdel-Aziz said the decree is likely meant to ease political pressure on Morsi just days ahead of a protest rally against the president planned for Friday.