Bieber, 20, had an altercation with the 'Lord of the Rings' star at a party in Ibiza on July 30, after he made a reference to the actor's ex-wife Miranda Kerr, reported Contactmusic.
The singer was romantically linked with Kerr during her marriage to Bloom.
"Obviously we're all young and he gets himself into some stuff sometimes. He's a person I'd go to for everything. He's like a big brother," Simpson said on a chat show.
He added that Bieber has done a lot of good for people so his mistakes can be overlooked. "He has the world in his hands as he does a lot of good as well. I've got all good things to say," he said.