"The average price per ad was 123 percent costlier in the second quarter of 2014 compared to last year," Dave Wehner, Facebook CFO, said in the latest earnings call.

Facebook also displayed 25 percent lesser ads but revenues from advertising still increased by 67 percent.

"The price of ads correlates to the value that they create. We continue to focus on making those ad units better and better, more relevant and targeted for the people who use Facebook, as well as for marketers," Wehner added.

A design change in April this year left lesser space for advertisement on a page. The company said "people will see fewer ads on Facebook so some advertisers may see increased prices at auction".