Consumers have long been asked to confirm their online purchases, but now Google Inc. is asking them to also confirm the ads they click on.

As part of an effort to curb the rising number of ads accidentally hit by errant fingers on smartphones, the search engine giant said Monday it’s introducing “confirmed clicks” into all ad banners appearing inside apps on smartphones. The feature will prompt the user to confirm whether they intended to visit the advertiser’s site. In an official blog post Monday, Google GOOG, +0.34% acknowledged that some people are clicking on smartphone ads by mistake because the screens are so small.