The Cameroon international played under Guardiola at the La Liga giants in 2008-09, but said the Spaniard barely spoke to him.
Zlatan Ibrahimovic labelled Guardiola a 'coward' in his autobiography, which was released last year.
Eto'o said the 43-year-old often communicated to him through other players because he was afraid.
"Guardiola has never had the courage to say things in front of me. He passed by the players," Eto'o told beIN Sports.
"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.'"
Eto'o said that while Guardiola greeted him when he was at Inter and the Serie A giants were playing Barca, it was just for show.
"He shook hands with me when I was at Inter and I played against Barca, but this was just for the cameras and TV," he said.
"Behind the scenes before the match, he did not greet me."
Eto'o criticised Guardiola for failing to learn about the dressing room prior to his arrival.
The 33-year-old recalled telling Guardiola, who won multiple leagues and cups and a European Cup with Barcelona, he had never reached great heights as a player.
"I first of all reminded Guardiola that he'd never been a great player. He was a good player, that's true," Eto'o said.
"I told him, as a coach, he had proven nothing. He came in and didn't even know the story of the dressing room."
