Gabriel believes Arsenal will be capable of mounting a serious title push this season after fading away over the past three seasons.
"I don't think we can give excuses," Gabriel, 27, told BBC Sport. "We did everything we could in the last three years. I feel like we had a little bit of bad luck sometimes, but we all believe that we can win big titles.
"We're focused on what our manager is telling us to do, and what we have to do, and what we have to improve. I think this year will be different."
New signings make us stronger
On their new additions, Gabriel said: "I think the players that came will help us out a lot.
"The club is doing what is best for the players and the manager. They are definitely doing their best to bring the best players that can help us, but we have to focus on what we can do out on the pitch.
"The players that are here are doing that. We are strong and we are getting stronger with these new players.
"Definitely, it excites me. We want to have the best players. To be in the dispute for titles, you have to have the best players."
He added: "I am here to win big titles and I do believe that this season will be different. We have let a couple of titles slip through our fingers recently.
"We almost won but I think this year, things will be different. I have a lot of faith in that."