The man, who would not give his name, is against a 225-bedroom hotel being built at a derelict site descending from Victoria Street to the Cowgate.
The development would see the India Buildings regenerated alongside neighbouring structures.
Built in the 19th century, the A-listed properties are often seen as one of the city’s hidden architectural gems, boasting a range of stunning original features as well as the former registry office that hosted Scotland’s first ever same-sex civil partnership.
Overall designs include restoring the nearby B-listed Cowgatehead Church and turning it into a bustling function space and venue, as well as saving a further C-listed building.
A Police Scotland spokeswoman confirmed they are in attendance at the scene.