In an interview with the BBC, Mr Obama said it was "distressing" not to have made progress on the issue "even in the face of repeated mass killings".
He vowed to keep trying, but the BBC's North America editor Jon Sopel said the president did not sound very confident.
However, Mr Obama said race relations had improved during his presidency.
Hours after the interview, a gunman opened fire at a cinema in the US state of Louisiana, killing two people and injuring several others before shooting himself.
In a wide-ranging interview, President Obama also said: » | Friday, July 24, 2015
