The Department of Infrastructure is ordering TT campervans not to camp overnight on Douglas Promenade.
This morning, workers left notes on a number of vehicles saying the parking spaces are for cars only.
The letters ask people to move their vans immediately and say there are dedicated campsites around the Island.
They add the DOI is worried people are pouring waste into surface drains and causing environmental damage.
Warning over parking suspensions for King's visit
Peel residents outraged over toxic powder spread near young gull
Commissioners tackle beach rubbish after online criticism
This year's bookings will be honoured, says closing venue
Noel tackles charity car wash for Autism Initiatives
TT legend's bike could fetch up to £55k at auction
Southern road temporarily closed this week
Number registered with GPs has risen by 1.7 percent