Zuniga's knee connected with the back of the Brazil forward during Colombia's quarter-final, which Brazil won 2-1, last Friday.
Neymar was carried from the field on a stretcher and it was later confirmed the Barcelona man had cracked a vertebra and would miss the remainder of the tournament.
Zuniga insisted it was never his intention to harm Neymar, but the news of the injury has provoked outcry from the Brazil camp, with captain Thiago Silva branding the challenge "cowardly".
However, Napoli, who signed Zuniga from Siena in 2009, released a statement on Tuesday to outline their backing for the 28-year-old.
"Napoli are sorry for the accident that occurred that will prevent Neymar from playing in the semi-final against Germany," the statement read.
"For the Brazilian champion [Neymar] we send best wishes for a speedy recovery.
"At the same time, the club expresses its support for Camilo Zuniga, subjected to fierce criticism and threats of all kinds, for a foul in play that was not malicious but unfortunate in its consequences.
"We note with relief that, in addition to the referee and his assistants, also the FIFA Disciplinary Commission has found that the foul was not malicious."
