In a video message posted on her Instagram page, Lexi, who essayed Morgan Stark in the movie, says: "Hi, I'm Lexi Rabe, and I'm only 7 years old. And I mess up sometimes, so my mom and dad give me tonnes of talking tos and timeouts, believe me.
"And if I go anywhere and I'm acting a little silly or messed up or anything like that, I'm just 7 years old. Please don't bully my family or me."
She ended her message by quoting the "love you 3,000" line from "Avengers: Endgame".
Her mother Jessica also wrote an elaborate post asking bullies to keep away.
"I hate that we even have to post this. But yet again Lexi's getting bullied. And this kind of thing makes celebrities never want to leave the house, never want to meet people. Please keep your opinions to yourself so Lexi can grow up in the free world.
"She's a normal human being and she's a child. We give her a talking and we give her timeouts but we don't do that in public. Sometimes we are rushing from place to place stressed like everyone else to get to set on time or work or whatever and we seem a little grumpy. I'm sorry if you see us this way but that's life!
"If you ask us for an autograph, we always almost say yes. If we happen to be having a bad day that might put us right on the right! We are not perfect! These perfect children are not being given the freedoms and the rights that they should. If your child is so scared to be themselves in public and mess up a little then you're over-parenting.
"We give our children plenty of rules and boundaries but then give them the freedom to mess up and learn from their own mistakes. They would not be on set an on movies if they weren't well behaved. Trust me they have no desire to hire kids like that. And there were plenty of children that productions can work with. So if you see us in public and think you have the right to judge. Wait. Number one, until you have children of your own, and number two we realize that we're not perfect and we're not claiming to be.
"But just try to realize the different strokes for different folks... what you do with your kids may work for you and what I do with my kids works well for me. My children love me and respect me even if they act out sometimes. Thank you."
( With inputs from IANS )