The (Norfolk, Va.) Virginian-Pilot reported Thursday Kahne, who lives in Mooresville, N.C., deleted some of the comments for which he had been criticized and apologized on Facebook.
"I understand that my comments regarding breastfeeding posted on Twitter were offensive to some people," he said. "For that, I apologize. It was in no way my intention to offend any mother who chooses to breastfeed her child, or, for that matter, anyone who supports breastfeeding children."
He said reading Twitter followers' "feedback" gave him a "better understanding of why my posts upset some of you."
Kahne, 31, said his posts were "just a reaction to the location of that choice [to breastfeed], and the fashion in which it was executed on that occasion," but added, "I respect the mother's right to feed her child whenever and wherever she pleases."
Kahne was shopping Tuesday at a grocery store when he spotted the woman breastfeeding and said on Twitter: "Just walking through supermarket. See a mom breastfeeding little kid. Took second look because I was obviously seeing things. I wasn't!"
He then said on Twitter, "I don't feel like shopping anymore or eating."
Fox Sports reported somebody responded on Twitter, "I hope someday you have a kid and someone tells your wife that feeding your child looks nasty."
His response included an expletive, Fox Sports said.