Aston Villa assistant Keane was captured on camera looking unimpressed when Chelsea manager Mourinho approached him and boss Paul Lambert shortly before the end of their team's 3-0 defeat at Stamford Bridge last month.
Mourinho - no stranger to mind games with other managers - regularly looks to conclude post-match formalities with his opposite number prior to the final whistle, and often heads down the tunnel while the game is still going on.
And, speaking at the launch of his new book in Dublin on Thursday, Keane labelled the Portuguese's actions "disgraceful".
"I don't mind all that [Mourinho's mind games] but the game is still going on," said the former Manchester United captain.
"It's disgraceful. I've seen him doing it to other managers - it is a disgrace. The game is still going on.
"You wouldn't do that on a Sunday morning, you would get knocked out."
When questioned further on whether he perceived Mourinho to be disrespectful and arrogant, Keane added: "What do you think? That's a stupid question."
