Giovinazzi has failed to match teammate Kimi Raikkonen so far in 2019, with the Finn scoring points at all three Grands Prix this year.
Giovinazzi is yet to finish inside the top ten, but has endured a couple of difficult weekends, none more so than last time out in China.
The Italian was forced to sit out both the opening practice session and qualifying due to a recurring power unit issue.
"Kimi is doing a great job, his feedback to engineers is as precise as it can be and as soon as he sits in the car he gets the job done," Vasseur said.
"Antonio so far couldn’t show his real potential, but that’s completely down to the team.
"Some technical issues and therefore missed track time meant that he could never get comfortable and get the best out of the car, but especially in Australia in Q1 he showed how fast he is.
"Everyone just needs to be a bit patient and I’m sure he’ll come around."
Vasseur says that the target is clear for Alfa Romeo heading to the Azerbaijan Grand Prix, as it targets getting both of its cars inside the top ten on race day.
Baku means crashes and safety cars and overtaking so you’ll never know what to expect from the race, but our target is clear," he said.
"We’ve put a lot of work into the development of our performance since the race in China so we want to finish in the points with both cars.”
Bahrain International Circuit - Winter testing
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