The former blaes playing fields in Victoria Park are being marketed in an online advert.
Glasgow City Council said last year it was considering renting out park facilities in a bid to generate funds.
Property consultants Ryden, which completed a feasibility study on Victoria Park, said potential uses included a retail development, a pub or restaurant, a garden centre, an open air market or children's soft play.
Park-goers are worried they will end up with a large commercial development they have no say in.
Cathie Russell, 59, said: "The council said they would consult on it - but there's a big difference with doing that and then advertising it.
"I don't want to see any building on it, unless it was a small one for community use."
Ms Russell said she believed most people wanted to make the use of the open green space.
Surveys conducted by Anniesland MSP Bill Kidd last year found 69 per cent in favour of an orchard.
Councillor Kenny McLean, Partick West SNP councillor, said: "I am concerned that the way this is being done will mean it could be opened up for commercial use."
A council spokesman said: "Local elected members, local community councils and Friends of Victoria Park have been kept abreast of any developments."