The game appeared on a number of file-sharing websites over the weekend, leading to YouTube videos showing off the in-game racing and player customisation.
The videos have since been removed from YouTube, while RedLynx issued a statement assuring fans that the footage did not represent the final game.
"Unfortunately there has been some unofficial information coming out ahead of the development process. We assure you we are aware of these and will be tackling the issue with our partners," reads the statement.
"Here is an important thing for you to know: the leaked version does not have any online functionality, which is crucial to the Trials experience. Lead boards, friend challenges, online multiplayer and global track sharing are all fundamental features of the game which cannot be fully experienced ahead of launch.
"Even single-player uses an asynchronous multiplayer feature in a new way. Without these core online features, the game cannot be experienced properly before launch."
Promising a new trailer soon, RedLynx urged fans not to post links to copyrighted material, including the unofficial gameplay videos.
Announced last June, Trials Evolution is a sequel to 2009 release Trials HD.
The upcoming release adds outdoor racing, competitive multiplayer and the ability to share custom tracks with anyone in the world.
Trials Evolution will be released later this year.
Watch the Trials Evolution teaser trailer below: