The Lotus driver hit the wall for the first time on Thursday during free practice two, before repeating the effort on Saturday morning in the final minute of the third practice session.
The team managed to repair the car just in time for Grosjean to take part in qualifying, where he locked down 13th on the grid.
"I think I made some mistakes [in practice]," he admitted.
"The car is performing very well, but it was a bit on the edge to start with. Through the weekend we've improved.
"It's not always easy to know exactly what's going on, and Monaco is very bumpy and very unpredictable. But it didn't hurt the confidence, as you could see in Q1."
Grosjean's Lotus team-mate Kimi Raikkonen will start Sunday's race from fifth, and is confident of moving forward.
"I think the car was the best it's been this weekend [in qualifying]," he said.
"We will have to see what will happen, and what the weather will be. Hopefully we can pick up some places.
"If we can get the tyres working a little bit better, we can be fast."