By Jill Serjeant

LOS ANGELES (Reuters) - Even some young Disney Channel stars, as popular as they seem to be, have suffered at the hands of bullies, and now dozens of them are urging kids to stand up against bullying - not by lashing out, but by speaking up.

In a campaign launching on Thursday on Disney Channel, Disney XD and Disney.com, actors like Billy Unger, Bridgit Mendler and Bella Thorne are urging 6 to 14-year-olds to treat each other better, both in the playground and online.

The campaign also encourages parents to teach their children how to use cell phones, social networking sites and gaming websites responsibly, and gives advice on what to do when cyberbullies strike.

Unger, 16, who plays a bionic teen in the hit Disney XD series "Lab Rats", recalls in one public service announcement for the campaign how he was taunted with nicknames like "small fry" and "shortie" when he was in elementary school.

Unger told a teacher who met with his parents. But what also helped, he said, was a casting agent telling the budding young actor that being short was a good thing for a kid entering the entertainment industry.

"So from that point on, when people called me small fry or shortie I was like, 'yeah, you're right and I am proud of it,'" Unger says in his message.

China Anne McClain of "A.N.T. Farm", Zendaya of "Shake It Up" and Debby Ryan of "Jessie" are also taking part in the Disney campaign, run jointly with the non-profit group Common Sense Media.

KIDS INSPIRED BY OTHER KIDS

"When kids see other kids who have had experiences they can relate to, that is so much more profound and inspiring than hearing from an adult," said Caroline Knorr, parenting editor of Common Sense Media.'

"These Disney Channel characters are real people, and kids really look up to them ... So for them to come out and say 'this happened to me' or to advocate for good digital citizenship, it will make a huge impact," Knorr said.

Disney Channel SVP of original programming Adam Bonnett said the family friendly network felt it had a duty to speak out against cyber-bullying.

"As the media platforms and viewing patterns of our audience become more interactive, it's become more important for us to reinforce the significance of positive social communication," Bonnett said.

The campaign, which is expected to run for several months, directs kids and parents to a dedicated website www.Disney.com/commonsense for information and advice.

"We don't advocate responding or retaliation because we feel cyberbullies are looking to get a reaction and it is best to just ignore it," said Knorr, who advises kids to turn off their phones, or block access to online "friends" who turn nasty.

Although confiding to a teacher or trusted adult is important, Knorr said 'tweens and older kids often prefer to turn to friends first, rather than parents.

"Kids are reporting that it is way more important to have peers support them in a bullying situation than parents. The instinct for parents is to rush in and try to fix everything."

But parents also have a huge role to play.

"Parents really need to have a conversation with their kids, when they give them a cell phone or allow them do social networking, about what responsible behavior is.

"These are not toys. You can't just hand your kid a cellphone and assume they will use it responsibly," Knorr said.

(Reporting By Jill Serjeant; Editing by Bob Tourtellotte)