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."
'You couldn’t blame Trent Alexander-Arnold if he wanted to play for Real Madrid – I hope he stays, but even with Mo Salah, I would understand if he decided to leave': Former Liverpool defender explains why he’s braced for key Anfield exits
‘Sven asked if I’d like to play for England – even to be considered made me proud, but I don’t think they really wanted a foreign player in the national team’: Former Premier League star reveals conversations over converting nationality
