City defeated rivals United 3-0 at Old Trafford, with Haaland scoring two goals and provided an assist for Phil Foden for the third goal.
After the game Haaland was spotted deep in conversation with boss Guardiola, appearing to talk about his second goal.
Haaland headed past Andre Onana towards the back post and appeared to maybe have jumped too early, although still netted.
It looked as though Guardiola was offering some advice on how to improve his technique, but Keane was not happy with what he saw.
Speaking on Sky Sports, via talkSPORT, he said: Its all for show this, this is all for show, Id have that chat in the dressing room, whats the big deal?
Its a lovely header but you dont need to be on the pitch talking about it for five minutes. Just get down the tunnel and enjoy your victory.
Sundays win was Citys seventh win at Old Trafford under Pep Guardiola.
Only against Arsenal (8) has Guardiola won more away games against a single opponent in his managerial career.
City move up to third place on 24 points, just two points adrift of leaders Tottenham Hotspur after 10 games played.
Up next for United is a fourth round home clash with Newcastle United in the Carabao Cup.
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