The Gunners had won their previous 10 matches in all competitions before they were held at The Hawthorns on the weekend.
"It's time for us to start a new run," he told the club's official website. "Hopefully we can win the next game and the few more after that, and create the momentum again.
"We're still top of the league so the momentum is still with us. We won't lose our confidence."
Arsenal continue their league campaign on October 19 when Norwich City visit the Emirates Stadium.