The Prime Minister said parents needed to boycott "vile sites" after the father of a cyber-bullying victim called for more regulation of social networks on the internet.
Hannah Smith, 14, from Lutterworth, Leicestershire, was found hanged on Friday after being bullied on website ask.fm.
David Cameron said: "There's something all of us can do as well as parents and as users of the internet and that is not use some of these vile sites, boycott them, don't go there, don't join them.
"I'm very keen we look at all the action we can take to try and help stop future tragedies like this."
The father of Hannah Smith, who committed suicide after being bullied on the Ask.fm website welcomes the site's new cybersafety measures.
Major organisations have withdrawn adverts on social networking site ask.fm following the suicide of teenager Hannah Smith.
Maybe it's time we all had a reality check, to look up from our screens, lose the masks we all wear online, and look at each other.