"We urge those holding Emilio Morenatti to release him at once. We also call on Palestinian officials to do everything in their power to see to it that our colleague is returned safely," the New York-based group said in a statement.
The 37-year-old Associated Press photographer was kidnapped on Tuesday by four masked gunmen off a Gaza City street in the latest abduction of a Westerner in the increasingly lawless Palestinian territory.
No group immediately claimed responsibility for the abduction.
"We're dismayed that journalists have become pawns of Palestinian groups seeking to exploit them for political purposes," CPJ Executive Director Joel Simon said in the press freedom group's statement.
"These blatant attacks on journalists will have a chilling effect on their ability to do their work and will ultimately deprive the world of information about this critically important story," he added.
Morenatti's abduction is the latest in a string of kidnappings of Westerners in the Palestinian territories, which have been plunged into an unprecedented financial and political crisis since Hamas formed a government in March.
Westerners have previously been kidnapped as bargaining chips in demands on the Palestinian Authority and are usually released unharmed within days.

Copyright AFP (Agence France-Presse), 2006