The Gunners do not have a game until a week on Wednesday in the UEFA Champions League last-16 at Bayern Munich.
And Mertesacker, who scored the Gunners' consolation goal in the 2-1 derby defeat to Spurs, says the squad needs to use the break to regroup.
"We need this breather now," he told the London Evening Standard. "We have 10 days until our next game so we can think about our situation. Of course there is potential but we need to show that.
"That's what we need in the next few weeks. To go to Munich, to show responsibility for the Champions League, take the chance there and afterwards we have to take care about the league and try to go for all points.
"We were good in the beginning (against Spurs) but we need to maintain that level and that's what we are lacking all the time, that consistency over 90 minutes or at least to keep a clean sheet for the first 45 minutes."