Residents reported seeing the travellers setting up camp in Ashton Park on Sunday evening (June 19).
Pictures show at least three caravans moved onto the park – located to the west of Preston.
Coun Robert Boswell, Cabinet Member for Environment and Community Safety, said: “It is regrettable that once again, our parks have been negatively affected and we hope the matter will be resolved soon and when that happens, we have very limited environmental impact.
“Council officers have served notice to leave on the group and will commence the eviction process once the welfare checks have been carried out.
“The police have also been informed.”
Reacting to the news, one resident said: “Leave them be. They are not causing any problems and need to live somewhere.”
Another agreed, adding: “Leave them to it. Causing no harm to nobody.”
But some residents were concerned about the mess they may leave behind.
One person wrote: “Hope they don’t leave another mess.”