The batsman became the first player ever to be suspended worldwide for being found guilty of breaching the ICC's strict code of conduct rules on racial vilification during Wednesday's game in Brisbane.
ICC match referee Clive Lloyd said Lehmann could have been given an eight-match ban but received a lesser penalty because of his previous good record and because he had apologised to the Sri Lankan team.
"Darren's comments could be interpreted as deeply offensive and I do not think that we can condone such things in sport or life in general," Lloyd said.
"He does have an impeccable record but the point is we have a code of conduct and we must abide by it."
Lehmann's ban means he will miss the rest of the triangular one-day series with Sri Lanka and England, and possibly Australia's first game at the World Cup in southern Africa.
The Yorkshire and South Australia captain was found guilty after a three-hour hearing in Adelaide on Saturday morning.
The 32-year-old, reading from a prepared statement, told reporters he would not appeal against the decision.
NO APPEAL
"I accept the penalty handed down and would like to say once again how regretful I am that the incident took place," said Lehmann.
"I meant no offence by my comments and again would like to apologise for making them. I would also like to thank the Sri Lankan team for their support and understanding in this matter."
Lehmann was reported to Lloyd after he was overheard making an offensive remark about the Sri Lankans when he was alone in the dressing room after being dismissed.
He immediately apologised to the Sri Lankans for his outburst then provided a formal, written apology once the match was over.
The Sri Lankans said they had accepted Lehmann's apology and did not wish to take the matter further, but the ICC decided to charge him anyway.
The Sri Lankan coach Dav Whatmore told the hearing his players held Lehmann in high regard and did not want to see him suspended.
"I don't think we wanted to make an example of anybody, the point is we have to abide by a code and it doesn't matter who you are," Lloyd said.
"As sportsmen we have to show the way, we have to be above those sort of things."
Lehmann's lawyer Greg Griffin said the left-handed batsman should not be branded as a racist.
"(It) is an unfortunate outburst for which he has paid a very high price," Griffin said.
"This was a comment not made to any person and was made basically to a wall.
"Darren is not a racist, he doesn't have a racist bone in his body and that's why it was so important the Sri Lankans were so solid in...support of him."
