Children should be allowed to play outdoors more, with park rangers being employed to ensure greater safety in playgrounds, the Conservatives say.
Public spaces like playgrounds need more supervision, the Tories say
The party has launched a Childhood Review, setting out plans to make parks and streets more secure from bullying, crime and other dangers.
It is urging councils not to put up "no ball games" signs or treat children playing outdoors as a nuisance.
The government says parks have improved and neighbourhood wardens cut crime.
But Unicef has ranked the UK the least child-friendly of 21 rich nations.
Conservative leader David Cameron said: "Parents have lost confidence that their children will be safe on the streets and in our public play areas. This is not some irrational fear to be educated out of them.
"It is an understandable reaction to everything that goes on - from more traffic to the way gangs can take over children's playgrounds."
He added: "Adults' natural authority, good sense and positive instincts have been dangerously undermined, so adults no longer feel any right, or any responsibility, to constrain children's behaviour if they are not their own. This is a disaster for our society, and we have to reverse it."
The Conservative review's proposals include:
The review's author, shadow universities and skills secretary David Willetts, said the outdoors seemed "hostile" to children and parents because of fears over crime, bullying and traffic.
- Increased adult supervision of public spaces, such as park rangers to ensure playgrounds are kept clean of syringes and broken glass and do not become a gathering place for gangs
- Changes to the British Crime Survey, so that it measures crimes against children, which are currently excluded
- "Walking buses" to take groups of children to and from school
- More visible policing on the streets, by cutting back on the bureaucracy which keeps officers behind a desk;
- Councils and police to take a sensitive approach to children playing outside, to create "safer neighbourhoods, not neighbourhoods without children".
- Action on traffic to make streets safer for children.
This forced young people into a "flat world of screen-based activities, or they end up being driven around to supervised play".
Mr Willetts said: "Britain is the least family-friendly country in Europe. We want to make it the most family-friendly."
Communities Secretary Hazel Blears said most people were satisfied with their local parks and there were plans to improve public spaces in deprived areas and put more green spaces in new housing developments.
"This government put a stop to years of disappearing parks and green spaces and successfully turned around that decline in many places. This includes investment of over £24m," she said.
And she said neighbourhood wardens had been successful in reducing crime and anti-social behaviour by providing a "visible, uniformed presence in parks, high streets and other public spaces".
Bob Reitmeier, chief executive of The Children's Society, said: "The Conservatives' proposals are a welcome addition to the ongoing debate on the state of childhood in the UK.
"What is now required is a wider culture change, which tackles the current climate of fear and restores adults' trust in children and each other."