Cumbria Police said that from Wednesday anyone in the vehicles they think is "on holiday" will be "advised to go home" and could be fined.
The force has previously said the outbreak is "no excuse for a holiday".
The government is ordering people not to leave their homes unless it is absolutely necessary.
Assistant Chief Constable Andy Slattery said: "We will be stopping anybody coming into the Lake District who we think is coming in on holiday with caravans, camper vans, or whatever, and advising them to go back to their home address."
He issued a warning on Saturday urging tourists to stay away from after many ignored advice to social distance.
The government has said everybody should stay at home and will only be allowed to leave for specific reasons:
- Shopping for "basic necessities" as infrequently as possible - but people should use delivery services where they can
- Medical reasons, to provide care, or to help a vulnerable person
- Travelling to and from work, but only if it is "absolutely necessary".
People should not meet friends or family members who do not live with them.