More than 550 people have signed petitions calling on the UK Government to ensure there is no further access restriction to Cape Wrath.
Local firms are concerned by the MoD's plan to buy the last piece of the famous peninsula it does not own.
The Northern Lighthouse Board is selling off 58 acres round Cape Wrath Lighthouse and some of the buildings.
The community-led Durness Development Group registered an interest under Land Reform legislation five years ago to ensure it would have first refusal if the assets came on the market.
However, when it attempted to renew its interest it found the lighthouse board was in negotiations with the MoD.
The ministry already owns the rest of the cape, which is used as a bombing range.
For decades the MoD has closed off public access to Cape Wrath for around 130 days a year during military exercises.
In a letter to Caithness, Sutherland and Easter Ross LibDem MP John Thurso, the Minister of State for Defence Personnel Mark Francois seemed to announce that would change if the MoD gets the 58 acres.
It would mean "... for reasons of health and safety, any access by the local community would be precluded."
Members of the community are deeply concerned, as many firms depend on visitors. But an MoD spokesman said: "The MoD has shown an interest in the site at Cape Wrath and is aware a community right to buy application is under consideration with the Scottish Government.
"The MoD is awaiting the outcome of this application and no action will be taken ahead of a decision being made. However, should the site be purchased by the MoD, there are no plans to restrict public access further than present arrangements."
Mr Thurso said: "I find it hard to believe the MoD would want to do this given the relatively harmonious relationship it enjoys with the community, but we need to get clarification.
"I hope the Scottish Government has taken notice of this and will permit a community buyout which would put the issue into the long grass for good."
A Scottish Government spokesman said a decision would be made once ministers had considered the case.