"Never stop being a good person, even to the unkind ones," the mother-of-four posted via her Instagram Story.
The potential jab at her older sibling came after Kourtney spoke on this Thursday's episode of The Kardashians about how their relationship turned rocky after her extravagant Italian wedding to Travis Barker.
"She wasn't happy at my wedding," the reality TV star claimed of Kim. "Everyone else was like, 'Whoa, this is amazing. We're having the best time.'"
"She can never give acknowledgment of like, 'Whoa, this is so amazing.' She sees everything that I had there and takes it for her own, and she doesn't even see it. She sees it for the dollar signs, but to me, I see it. And I see it like, 'Oh, you were there, you weren’t happy,'" the mother-of-three explained.
"Everyone said something to me, all my friends, they were all like, she's spiraling," Kourtney shared.
The argument between the two women began after Kim did a Dolce & Gabbana collection shortly after Kourtney's May nuptials, which the latter saw as a personal dig since the brand designed her wedding gown.
"This was my wedding and how I lived my life every summer," she noted. "If I did it to Kim, she would freak out. To me, it was more personal."
"I think that's why it hurts my feelings, because it was my actual wedding. The year your sister got married, you then made a deal to do this fashion show? Don't do it the same year that comes out four months later," the brunette beauty complained.
"It's not like I did their campaign, and then she did the campaign right after. Like, who cares? That's business, it's my actual wedding, and that wasn't a business deal for me. I did it because it felt really personal," she concluded.
Meanwhile, Kim does not seem to have understanding for her sister's qualms regarding the fashion campaign.
Never miss a story — sign up for the OK! newsletter to stay up-to-date on the best of what OK! has to offer. It’s gossip too good to wait for!
"I couldn't have been more mindful and said don't do certain collections out of respect for Kourtney," Kim said on the episode of what she told the brand.