SOPA Images/Getty Images Pro-Palestinian activists have accused social media sites, including Facebook, of censorship. In a coordinated effort, they've tanked ratings on the Facebook app. Apple denied Facebook's request to remove the negative ratings, NBC News reported. See more stories on Insider's business page. Apple refused a request from Facebook to remove negative reviews in the App store after pro-Palestinian protesters coordinated an effort to tank ratings because of censorship of Palestinian content, NBC News reported. On Saturday, the Facebook app had a 2.3 out of five-star rating in the App store compared to a more than four-star rating last