The U.S. Federal Trade Commission won't block Google's $750 million attainment of cell phone advertising dealer AdMob because the deal isn't likely to harm rivalry in the rising mobile advertising market, the agency.

Google's attainment of AdMob, announced in late 2009, merges the two leading mobile advertising networks in the U.S., raising "serious antitrust concerns," the FTC said in a statement.

But Apple's announcement in April that it would launch its own ad network "overshadowed" the antitrust worry that the FTC had about Google's AdMob acquisition, the agency said.

"As a result of Apple's entry AdMob's victory to date on the iPhone platform is improbable to be an correct predictor of AdMob's competitive meaning going forward, whether AdMob is owned by Google or not," the FTC said in a statement.

Some other companies show to be rising or obtain smartphone platforms to better compete against Apple's iPhone and Google's Android, the FTC said. These companies would have a strong inducement in maintaining a competitive mobile advertising industry, the FTC said.