The Pwllheli North Quay properties were targeted overnight, with the warning sprayed with black paint.
It is understood that the houses were empty at the time of the attack.
Images of the houses have been posted on social media, with many residents saying they are “embarrassed” by the law.
The culprits were criticized on Facebook, several people stressing that to write the graffiti, they themselves would have flouted the rules for locking coronaviruses.
Local Coronavirus News
Gwynedd’s advisor for Pwllheli, Hefin Underwood, said, “Waking up is embarrassing.
“Many of these homes are purchased locally and one is used as a local business.
“The police are working hard with the local community to make sure people are not visiting their vacation homes now to deal with them this morning.
“We don’t need it in Pwllheli. “
North Wales police have confirmed that they have been informed of criminal damage in the area.
The graffiti has since been painted by local residents.
Cllr Underwood added: “The bottom line is that it has been washed and looks new thanks to a handful of us locals who are very proud of our little town. “
The graffiti attack comes amid growing tensions over tourists coming to North Wales, despite the fact that the Welsh and British governments have urged people to stay home to stop the spread of Covid-19.
Vandals slashed the tires of a car parked in a place of beauty in Abergele on Thursday and villagers from Penmachno this week confronted tourists staying in a rented Snowdonia Airbnb.
It’s something that has touched our whole lives at one point.
From the cradle to the grave, the National Health Service and the incredible professionals who care for us are part of British life.
Today, more than ever, we must cherish those who dedicate themselves to our care, without worrying about their own health, because they work tirelessly to care for people facing the coronavirus pandemic.
Nurses and others – employed by the NHS and all other parts of health and care – we never needed it anymore.
So let’s show them some love and create a living card of gratitude from all over Britain.
Click HERE to place a heart on the map and show that you appreciate the daily efforts in the NHS.
Thank you a million NHS workers – we love you.
Residents of Anglesey and Gwynedd confronted motorists who they accused of ignoring government advice to make only essential trips.
Join us to show your support and send a heart to the heroes of the NHS where you live by visiting the thanksamillionsnhs website.