It was hoped the size of the clothing optional section of coastline in Budleigh Salterton, Devon, would be increased after tidal activity rendered the current area "uncomfortable" to sit on.
But the town council blocked the move.
British Naturism said the decision was "ridiculous" and "offensive" to its members.
The council was unconvinced by the argument the tide had washed away pebbles on the beach and left rock behind, making it "too uncomfortable" for naturists.
Its foreshore and footpaths committee said naturists could still use the beach if they put a "towel or lilo down" and voted against extending it by 200 yards (183m) eastwards.
Andrew Welch, from British Naturism, said: "Naturism is not illegal and we don't need designated places so it is offensive for any social group like ours to be treated in this way.
"It harks back to the 1950s and we want to show these ridiculous authority figures that they are wrong and completely out of touch."
Town mayor Courtney Richards said if the nudist beach was extended it would be about 200 yards from the town's beach huts.
"Budleigh Salterton is a family friendly town and I feel it is something families could do without, so I have a problem with them coming nearer to the town," he said.
"And I think the majority of people in Budleigh Salterton would not want that either."
However, Mr Welch said the council should designate a new beach for naturists.
The closest alternative is Weston Mouth, near Branscombe, about 10 miles away.
East Devon District Council, which owns the beach, has also been asked if the site can be moved but has made no decision.
A spokeswoman said it would work with the town council on the request.
The "nude" section of Budleigh beach was first designated in the 1970s.

The date was set at a meeting in Irbil chaired by President Massoud Barzani.
A statement said voting would take place in the three provinces that make up the region, and "areas of Kurdistan outside the region's administration".
There was no immediate comment from Iraq's central government, but it has urged Kurds not to hold a referendum.
Moves towards outright independence have historically been opposed by the governments of neighbouring Iran, Turkey and Syria, as well as by the US.
In April, senior Kurdish official Hoshyar Zebari told Reuters news agency that a "yes" vote would not necessarily mean independence would be declared.
Mr Zebari said it would merely help Kurds press their case for "the best deal" on self-determination once so-called Islamic State (IS) had been defeated in Iraq.
Kurdish Peshmerga fighters have played a major role in the US-backed campaign against the jihadist group, which seized large parts of northern Iraq in 2014.
But while driving IS militants out of the country, the Peshmerga have taken control of disputed territory claimed by both Kurds and the central government.
It includes the city of Kirkuk and the towns of Makhmour, Khanaqin and Sinjar - locations where President Barzani's senior assistant Hemin Hawrami declared voting would take place in September.
Prime Minister Haider al-Abadi has said holding an independence referendum now would be neither in the Kurdistan Region's interest nor Iraq's.
"The desire of our Kurdish brothers to create a country of their own is their right... and nobody has the right to deter them," he was quoted as saying by the Kurdish Rudaw news agency in April.
"But holding a referendum at this time is not right as the war [against IS] still rages, the region's situation is not suitable, and some neighbouring countries believe this move poses a threat to the nation's security themselves."
The head of Iraq's ruling Shia coalition, which includes Mr Abadi's Dawa party, meanwhile warned against any "unilateral" moves in the disputed areas.
Naturists have branded a decision to deny their bid to extend a section of nudist beach as "old-fashioned".
[NEXT_CONCEPT]
Top government officials and political parties in Iraq's autonomous Kurdistan Region have agreed to hold a referendum on independence on 25 September.