The centre-back impressed with Huddersfield in the Championship last season before a move to the South Coast, where he has only made eight appearances.
All of his Premier League starts have come in the last three matches amid an injury to Adam Webster and Seagulls boss De Zerbi has called for more from 19-year-old Colwill.
“Levi has big, big potential,” he told reporters.
“He's a good guy and I think he can play even better. I think he's playing at 60 per cent now, I want to give him more confidence.”
Brighton travel to Everton on Tuesday after Alexis Mac Allister returned with a huge fanfare at the club’s training ground. A video posted to the club’s social media showed confetti cannons and a standing ovation for the Argentine champion.
De Zerbi admitted he is unsure if the midfielder will play at Goodison Park.
“Mentally, for sure Alexis can play,” he noted. “Physically, I'm not sure but we will see [Tuesday] morning.”
On increased transfer speculation surrounding Mac Allister, he added: “I am happy if he wants to stay with us until the end of the season and I think it is better for him. For us, for sure, but also for him because in this moment changing team in January can be a problem for him. For us, but also for him.”