US regulators said they would not charge Google with illegal bias in internet search, but won commitments from the tech titan to end its "most troubling" practices, officials said last week.
The US Federal Trade Commission said it was unable to bring a case against Google for manipulation of search results.
But it settled a separate case with Google that requires the company to allow rivals access to its patented technologies.
FTC chairman Jon Leibowitz said the action concludes a 20-month probe of the internet giant, accused by rivals of abusing its market dominance to snuff out competitors.
Mr Leibowitz said many of Google's critics "wanted the Commission to go further in this investigation and regulate the intricacies of Google's search engine algorithm."
But he said the FTC "exhaustively investigated allegations that Google unfairly manipulated its search engine results to harm its competitors," but found the evidence did not support an enforcement action.
"The facts weren't there under the law we apply," he said. Even though some rivals dislike Google search, he said "it doesn't violate the American antitrust laws." Google made "enforceable commitments" to change some practices criticised by rivals in a voluntary settlement.