Eto'o, who is expected to leave the Blues this summer, recently called Mourinho a "fool" after the Portuguese had questioned the official age of the 33-year-old striker.
The Cameroon international scored 12 goals in 35 games for Chelsea last season.
"Contrary to what a puppet says about my age, I am still physically fit," Eto'o told cafonline.com. "At 33, I feel real good. I have proven that I could do better than youths."
Eto'o has repeatedly suggested that he will be playing for a club in Europe next season.