WASHINGTON — In a strong move to protect the privacy of Americans as they use the Internet on their smartphones and tablets, the Federal Trade Commission on Friday said the mobile industry should include a do-not-track feature in software and apps and take other steps to safeguard personal information.

The staff report, which was approved by the commission, is not binding, but it is an indication of how seriously the agency is focused on mobile privacy. As if to emphasize that, the commission on Friday separately fined Path, a two-year-old social networking app, $800,000. It charged the company with violating federal privacy protections for children by collecting personal information on underage users, including almost everyone in users’ address books.

Together the actions represent the government’s heightened scrutiny of mobile devices, which for many Americans have become the primary way of gaining access to the Internet, rather than through a laptop or desktop computer.

“We‘ve been looking at privacy issues for decades,” said Jon Leibowitz, the F.T.C. chairman. “But this is necessary because so much commerce is moving to mobile, and many of the rules and practices in the mobile space are sort of like the Wild West.”