"These newly improved automated efforts will remove those Likes gained by malware, compromised accounts, deceived users or purchased bulk Likes."
Facebook has long given members the ability to endorse pages at the social network by clicking on "Like" icons.
High numbers of Likes can give "fan count" status to pages, particularly those dedicated to brands.
"A Like that doesn't come from someone truly interested in connecting with a page benefits no one," Facebook said.
"This improvement will allow pages to produce ever more relevant and interesting content, and brands will see an increase in the true engagement around their content."
Facebook expected that less than 1% of the fan count on any given page would be trimmed as a result of the crackdown on "suspicious Likes".