SAN FRANCISCO — Few big technology companies have dared to create online products for boys and girls ages 13 and under.

But on Monday, Facebook introduced an app, called Messenger Kids, that is targeted at that age group and asks parents to give their approval so children can message, add filters and doodle on photos they send to one another. It is a bet that the app can introduce a new generation of users to the Silicon Valley giant’s ever-expanding social media universe.

In doing so, Facebook immediately reignited a furious debate about how young is too young for children to use mobile apps and how parents should deal with the steady creep of technology into family life, especially as some fight to reduce the amount of time their sons and daughters spend in front of screens. On one side are parents like Matt Quirion of Washington, who said Facebook’s snaking its way into his children’s lives at an early age would most likely do more harm than good.

“I’m an avid social media user, but I don’t feel my kids need more social interaction,” said Mr. Quirion, 39, whose three children are between ages 3 and 9. “They need their personal time to process all the social interaction and learn to grow into mature people.”