The team have experienced a troublesome start to the season, with just eight points to their name from six races.
Romain Grosjean has picked up all of those courtesy of back-to-back eighth-place finishes but, with the Canadian track's long straights, Gastaldi believes the car's lack of power could be shown up.
"On track, it could be something of a challenge for us as it doesn't look to be a track which plays to our current strengths, but whether that is the case or not we will soon find out," he said.
Technical director Nick Chester agreed with his colleague, as did Pastor Maldonaldo, who is still searching for his first points of the campaign.
"It's probably going to be a bit of a tricky one," said Chester.
"On the one hand we're going to have the soft and super-soft tyres, which should be better for us. On the other hand Canada's got long straights, which we feel might not be great for us."
The Venezuelan - who has finished just three races this season - added: "It could be a difficult weekend for the team.
"We are not expecting to be at the top, simply because of the type of track and how we understand our car and its performance strengths and weaknesses."