Two teenage girls have been charged with wilful fire-raising at the Buckie Shipyard site.
Emergency services were called to the disused office building on Commercial Road at around 5.30pm on Sunday after reports of a fire.
Police said the a “five figure sum” of damage was caused and no one was injured.
Two girls were subsequently charged and will be reported to the Youth Justice Management Unit (YJMU).
Inspector Neil Campbell said: “I would like to thank the members of the public who assisted with this inquiry and to Macduff Shipyards for its assistance.
He added: “I cannot stress enough the dangers of starting fires deliberately – you don’t know how the situation will develop and the consequences could be fatal.
“As we get into the longer Summer nights, I would urge parents and guardians to please keep an eye on where youngsters are going and congregating. By working together we can make the area we live even safer.”
The site was last week purchased by Macduff Shipyards.
Managing director John Watt said: “We had bought the site from Moray Council only last week and had already started to work on the building. It is extremely disappointing that this incident has occurred so early into our ownership.
“We would like to thank the local community for the assistance they provided to the police.”