The fine would be the largest penalty ever levied on a single company by the U.S. Federal Trade Commission, the Journal said late Monday.
The charges involve Google's use of special computer code, or "cookies," to trick Apple's Safari browser so Google could monitor users that had blocked such tracking, the newspaper said.
Google disabled the code after being contacted by the Journal. According to Google, tracking of Apple users was inadvertent and did not cause any harm to consumers, the newspaper reported.
"The FTC is focused on a 2009 help center page. We have now changed that page and taken steps to remove the ad cookies," Google told the Journal.
Google also faces potential sanctions from other governments. It is being investigated by the European Union to determine if the company complies with Europe's stricter privacy laws, the Journal reported.
An FTC spokeswoman declined to comment to the Journal.
Google and FTC could not be reached for comment by Reuters outside regular U.S. business hours.
Copyright Thomson Reuters 2012