"We are optimistic because Fidel has won" the fight against his illness "and could return to work soon", he said.
But he added: "I can't give an exact date for when he could go back to work," he added. "That will happen when he has satisfactorily concluded his recovery period."
Perez Roque, who also worked as Castro's personal secretary for seven years, is reported to be in frequent contact with the ailing leader.
Ricardo Alarcon, the National Assembly president, also indicated recently that Castro could eventually return to some kind of public leadership role but without spending "so many hours making appearances and visits".
The comments followed a surprise call by Castro to a radio talk show hosted by Hugo Chavez, the Venezuelan president.
They were the Cuban leader's first live remarks since his surgery and ceding of power to brother Raul seven months ago.
The call on Tuesday night fuelled expectations that he could soon reappear in public.