In a presentation to media, police officials said there had been no trace of any flammable liquids such as petrol at the site of the blaze at the 63-storey hotel and residential block, close to the world's tallest building.
"The direct cause was an electrical short-circuit," police commander Khamis Mattar Al-Mazeina told reporters.
Firefighters tackle Dubai blaze after all-night effort, investigate cause
He declined to say whether the cladding - layers fixed to the outside of buildings for decoration, insulation or protection - had affected the development of the fire, and directed queries about building materials to the Dubai Civil Defence authority.
The building was quickly evacuated with only minor injuries reported, and authorities went ahead with a New Year's fireworks display at the 160-storey Burj Khalifa tower a few hundred metres away.
Flames shot skywards from one side of the luxury Address Downtown Dubai, owned by developer Emaar Properties which stands across a plaza from the Burj Khalifa tower where people had gathered for the fireworks show.
Huge fire engulfs Dubai hotel
In a statement, Dubai police said that the short-circuit which caused the fire occurred in an area between the 14th and 15th floors of the hotel at around 21.25 local time.
On the night, television pictures showed pieces of blazing debris raining down from The Address as evacuated occupants hurried away from the building, some running.
Emaar said on January 3 the fire should have "no material impact" on the company because the building and risk of fire were covered by its insurance.
Dubai ruler's son among firefighters extinguishing hotel fire
The company also said it had hired a local contractor, Dubai-based DUTCO Group, as a contractor to clear and restore the building.
Some experts have asked whether cladding - which is used widely on the towers which crowd the Dubai skyline - may in some cases make them more vulnerable to fire.
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