The actress tweeted on Monday that she was no longer going to attend events in Belgium and Germany.
"To my Belgian readers, so very sorry to miss the Antwerp Book Fair today but I can't wait to come back and eat fries with you. Much love," she wrote. "German readers: I am deeply sorry to miss tomorrow's event in Berlin. I am so grateful for your energy and support. Mit viele liebe."
The "Girls" star, 28, has been criticized for passages in her book, "Not That Kind Of Girl," that detail experiences she had with her younger sister Grace when they were children.
In one paragraph, Dunham wrote that she offered her then-toddler sister "three pieces of candy if I could kiss her on the lips for five seconds ... basically anything a sexual predator might do to woo a small suburban girl."
In another, Dunham wrote that she "carefully spread open her [sister's] vagina" out of curiosity, about which Kevin D. Williamson of National Review wrote, "There is no non-horrific interpretation of this episode."
"The right wing news story that I molested my little sister isn't just LOL- it's really f****** upsetting and disgusting," Dunham tweeted. "And by the way, if you were a little kid and never looked at another little kid's vagina, well, congrats to you."
"Usually this is stuff I can ignore but don't demean sufferers, don't twist my words, back the f*** up bros," she added. "I told a story about being a weird 7 year old. I bet you have some too, old men, that I'd rather not hear. And yes, this is a rage spiral. ... Sometimes I get so mad I burn right up. Also I wish my sister wasn't laughing so hard."
A representative for Dunham said she had no further comment about the molestation claims.
Meanwhile, Grace Dunham recently wrote on Twitter, "heteronormativity deems certain behaviours harmful, and others 'normal'; the state and media are always invested in maintaining that."
"As a queer person: i'm committed to people narrating their own experiences, determining for themselves what has and has not been harmful," she added. "2day, like every other day, is a good day to think about how we police the sexualities of young women, queer, and trans people."