O'Donnell recently complained that Lauren is "unlikeable", criticised her romance with Puck for being unrealistic, and asked: "Why didn't they get a pretty heavy girl?"
Fink has now told Advocate that she was surprised by the comments.
"It's so crazy," she said. "Rosie's been talking about me for a bit now, and it was very positive. Then she was on Access Hollywood, promoting a new hairstyle or something, and for some reason she decided to talk about me again.
"I've been a fan of Rosie's for a long time... so I am surprised at the comments she made. I've got swagger too, so I don't find my storyline unrealistic. When I went to performing arts high school, I did date the cutest boy in school and I sang whatever song I wanted. My storyline has resonated with a lot of people, plus-sized and not, who don't feel 'other', so I'm honoured to portray Lauren."
Fink explained that she hadn't been hurt by O'Donnell's comments but added: "I'll possibly address it with her in the future. If I see her, I might be like, 'Woman, let's talk about this. Don't be jealous cause a big girl's doing her thing on Glee!'
"I love Rosie and I respect her opinion, so all I can say is that some of her comments were strange to me. But she was supportive originally, and I think she's still supportive - she did say that [executive producers] Brad Falchuk and Ryan Murphy are good navigators of this ship, and I agree.
"Besides, I don't write the show, so I don't have control over her complaints. But I'm really happy with my character, I'm proud to play her, and I'm having a blast."