Eto'o will meet up with Cameroon as planned on January 4, Inter said on their website on Friday.
Inter coach Jose Mourinho had wanted Eto'o to be available for the match at Chievo given Cameroon's first match in the tournament in Angola is not until January 13 against Gabon.
The Serie A leaders are now likely to try to wrap up the signing of Macedonia striker Goran Pandev in time for Wednesday's game having let reserve striker David Suazo join Genoa on loan despite Eto'o's impending month-long absence.
Pandev, who came through the youth ranks at Inter and has said he is close to returning to the San Siro, is a free agent after leaving Lazio following a contract dispute.
Eto'o will remain with Inter for a friendly in Riyadh against Al Hilal on Saturday, meaning he will not be present at former club Barcelona's parade of the six trophies they won in 2009.
"I was pleased to receive an invite from my ex-team mates but obviously tomorrow I can't be there because I have to be here with Inter," said Eto'o, who joined Inter from Barca in a swap deal with Zlatan Ibrahimovic in July.
