Jada Pinkett Smith says it's wrong for people to ''attack and criticise'' young stars such as Justin Bieber on social media.

The actress' 14-year-old son Jaden accompanied the 'Baby' singer on his controversial visit to London last week and Jada is stunned at the vitriol Justin and his peers like Rihanna, Taylor Swift and actress Quvenzhane Wallis have to tolerate online.

In an open letter on her Facebook page, she pondered: ''How can we ask for our young stars to have a high level of responsibility if we are not demonstrating that same level of responsibility towards them?

''Do we feel as though we can say and do what we please without demonstrating any responsibility simply because they are famous?''

The 41-year-old star - who has two famous children, Jaden and 12-year-old Willow, with husband Will Smith - went on to address the 'Never Say Never' hitmaker's troubled week in the UK capital, where he angered fans by being two hours late to the stage for one gig and got into a heated argument with a paparazzi photographer.

She wrote: ''Is it okay to continually attack and criticise a famous 19 year old who is simply trying to build a life, exercise his talents while figuring out what manhood and fame is all about as he carries the weight of supporting his family as well as providing the pay checks to others who depend on him to work so they can feed their families as well? Does that render being called a c*** by an adult male photographer as you try to return to your hotel after leaving the hospital? (sic)''

The 'Hawthorne' actress further criticised online abuse directed at the Oscar-nominated 'Beasts of the Southern Wild' actress Quvenzhane, who was referred to as a ''c***'' on Twitter even though she is just nine.

Jada also had harsh words for those who troll pop stars Rihanna and Taylor, both of whom have been involved in high profile relationships.

She added: ''Or what about our nine year old beautiful Oscar nominee who was referred to as a c*** as well? Or what about being a young woman in her early twenties, exploring the intricacies of love and power on the world stage? And should we shame a young woman for displaying a sense of innocence as she navigates through the murky waters of love, heartbreak, and fame?

''Are these young people not allowed to be young, make mistakes, grow, and eventually transform a million times before our eyes?''