Gyan picked up an injury in training on Tuesday that played a role in forcing the cancellation of a proposed friendly against German Bundesliga side Freiburg.
Ghana coach Avram Grant took the decision not to play the game in the wake Asamoah's knock over fears of injury to other key players, the Ghana Football Association (GFA) confirmed.
"The Black Stars were scheduled to play the Bundesliga side on Wednesday, hours before they depart for the tournament in Equatorial Guinea," GFA said in a statement.
"However, coach Avram Grant has decided to call off the friendly in the wake of the growing knocks suffered by players. The precautionary decision comes in the wake of the knock suffered by captain Asamoah Gyan during training.
"With some few days before the start of the competition in Equatorial Guinea, Grant has decided to protect his players from likely injuries."
Ghana are in Group C at the continental championships along with Senegal, Algeria and South Africa.
(Reporting by Nick Said in Cape Town; Editing by John O'Brien)