Leclerc started ninth in Saturday's 24-lap sprint, which commenced in intermediate conditions but ended on a drying track.
Amid a split between drivers who stayed out on inters and those who came in for slicks, Leclerc was in the latter camp but admitted he was "completely off the pace" with slicks in damp conditions.
The Monegasque dropped out of the top 10 to 12th at the finish, 50 seconds behind Red Bull's winner Max Verstappen.
"At the moment, I'm struggling like crazy whenever it's half dry, half wet with slicks, I'm just completely off the pace," Leclerc said. "So, we need to understand because now it's three races in a row that we find ourselves in those conditions and I keep struggling.
"I always seem to do something wrong with my driving style that doesn't help the car, and that makes me lose confidence. Then, I'm just really struggling. So it's a shame, but I will work harder than ever in order to be stronger in those conditions as soon as possible."
When asked by Motorsport.com to explain what his main problem area is, Leclerc replied: "It's mostly the balance at the end of braking, so at the entry or the corner, that's where I'm struggling the most. In the high speed especially, I had a few snaps where I nearly lost the car and yeah, I struggled a lot."
Leclerc has a fresh chance on Sunday in the main grand prix, having qualified second on the grid just half a tenth behind to Verstappen in his upgraded Ferrari. The race is expected to remain dry, which Leclerc says has boosted his chances of hanging onto a podium finish.
"A podium, yes. For the win is another story as I expect Red Bull and Max to be stronger, but a podium yes," said Leclerc. "If it's full dry or full wet, I know that in those conditions we are strong, and I feel good. But it's more in these in-between conditions that we are struggling."
