North Yorkshire Police said that they are still seeing children congregating together in evenings.
The force control room is also continuing to receiving reports of anti-social behaviour.
This is despite Prime Minister Boris Johnson's orders to stay inside and only leave homes to get food, for health reasons or for essential work.
He also urged people who did leave the house to practice social distancing - which means staying at least two metres away from each other.
Officers are now threatening to fine or issue dispersal orders if the young people do not follow the guidance.
Assistant Chief Constable Mike Walker said: "We are now at the stage where it is vital that our communities pull together to prevent the spread of COVID-19 and this includes our young people.
"Parents and carers, I’m appealing to you to speak to the young people in your families and ensure they are aware of the threat this virus poses, not only to our immediate families and communities, but our country as a whole.
"I realise and understand that staying inside together in our homes for long periods of time can be stressful and that young people may want to go out and see their friends. But please, encourage them to take responsibility for their actions, stay inside and use alternative forms of communication such as phones and social media apps to keep in touch with each other.
"Policing in our country has always been by consent and we rely on our local communities support to help us to keep North Yorkshire one of the safest places in the UK.
"We do not want to have to take an enforcement approach to this situation and issue dispersal orders or fines. But please be assured, if we have to resort to these measures, we absolutely will."