Scottish Borders Council agreed last month to take forward the plans for Victoria Park in Peebles.
It said that consultation and studies had shown it was the most suitable location for the facility.
However, Fiona Dalgleish, of the town's community council said, while the pitch was needed, it was not the right site.
SBC agreed last month that a planning application should be submitted for the third generation synthetic surface (known as 3G) with a view to completing construction in August next year.
Opponents, however, do not want to see part of the park turned over to the pitch.
"I totally understand and support the need for a 3G pitch, however I don't believe that public green space that is used by everybody should be compromised," said Ms Dalgleish.
"If the pitch goes in there, over a third of the green space in Victoria Park will become inaccessible to people who don't pay.
"It sort of goes against the grain of Scottish access laws - we should be encouraging people to utilise green space rather than fencing it off and making them pay for it."
Hundreds of people have signed a petition opposing plans to put a synthetic surface sports pitch on part of a Borders park.