Taken out of context in an Internet meme http://buzzpo.com/hours-after-paris-terror-attacks-meme-surfaces-that-calls-obama-out/. Two sources for the original quote are:
"At some point, we as a country will have to reckon with the fact that this type of mass violence does not happen in other advanced countries. It doesn’t happen in other places with this kind of frequency." * 2015-06-18
Statement by the President on the Shooting in Charleston, South Carolina
https://www.whitehouse.gov/the-press-office/2015/06/18/statement-president-shooting-charleston-south-carolina
"We are the only advanced country on Earth that sees these kinds of mass shootings every few months." * 2015-10-01
Statement by the President on the Shootings at Umpqua Community College, Roseburg, Oregon
https://www.whitehouse.gov/the-press-office/2015/10/01/statement-president-shootings-umpqua-community-college-roseburg-oregon
Cf. Obama in Paris on December 1st, 2015: "I say this every time we've got one of these mass shootings; this just doesn't happen in other countries." (Paris itself had just been "hit with a series of simultaneous terrorist attacks. The majority of 130 deaths were in mass shooting attacks, where the ISIS-affiliated terrorists attacked public places with automatic rifles." — as reported in * 2015-12-01
Obama Speaking in Paris: Mass Shootings ‘Don’t Happen in Other Countries’
Alex Griswold
mediaite.com
http://www.mediaite.com/tv/obama-speaking-in-paris-mass-shootings-dont-happen-in-other-countries/).
Misattributed
Variant: This [mass shootings] just doesn't happen in other countries.