Justin Bieber on Conor McGregor, 'We All Make Mistakes'

Justin Bieber isn't ready to write off Conor McGregor just yet ... telling TMZ Sports when it comes to the UFC's violent attack, "We all make mistakes."

Bieber has been following McGregor's career for years -- and publicly supported him when Conor fought Nate Diaz back in 2016.

He even vouched for McGregor's toughness before Conor fought his old friend, Floyd Mayweather.

So, when we saw Biebs out in Beverly Hills following a gym workout with his crew, we had to ask if he was concerned for Conor moving forward.

"I think Conor will be fine," Justin says ... "We all make mistakes."

The big question now ... will Dana White be as forgiving as Bieber when it comes to Conor's future?