The 33-year-old played under Guardiola at Barcelona in the 2008-09 campaign, but has revealed that the Spaniard would not speak to him directly.
"Guardiola has never had the courage to say things in front of me," Eto'o told beIN Sports. "He passed by the players.
"Xavi told me they wanted me to stay but I had to talk to Pep. I say 'never, if you do not respect me, I do not respect you.'"
This is not the first time that Guardiola has been criticised - the Munich coach was called a 'coward' by Paris Saint-Germain star Zlatan Ibrahimovic in his 2013 autobiography.