Bale, 27, was sent off for only the second time in his career after shoving Jonathan Viera while playing for Real Madrid against Las Palmas this month.
Wales travel to Dublin on 24 March for a pivotal match against Group D leaders the Republic of Ireland, who they trail by four points in third place.
"I'm not at all worried," said Coleman.
"Anybody sensible looking at him, he never does that. I don't even know what happened. But he is a human being and sometimes you do something and regret it."
Bale's red card against Las Palmas was his first since he was dismissed in Tottenham Hotspur's 2-1 defeat by Stoke City in October 2008.
His furious reaction to a push from Viera was in startling contrast to his usual placid demeanour.
And although Bale is frequently a target for robust challenges from opponents, Coleman does not believe Wales' talisman is affected by attempts to unsettle him.
"If you look at his past he has been kicked from pillar to post, so I won't be worried," he added.
"I remember when we played Scotland and some ex-Scottish player said 'He can't play if he hasn't got any legs'.
"I looked at that and thought, 'Does he really seriously think that is going to bother him?' If you look and see where he is playing, under the pressure, in the spotlight, week in, week out, so whatever the opposition have got planned for him, he's seen it before and dealt with it before."
Wales manager Chris Coleman has dismissed concerns the Republic of Ireland might attempt to rile Gareth Bale in their World Cup qualifier.