Arsène Wenger's side lie fifth in the table, and Koscielny says they must maintain their focus and belief over the coming weeks if they are to rise any higher.
"It is very difficult, it is a race and I think there are five or six teams who can finish in the top four," he told Arsenal Player.
"Every game you [look out for] the other scores, but if you don't win your match then it is nothing to see these results. It is very important to get the three points every time and then look for the other scores afterwards.
"Every weekend is difficult, it is a little war. It is very important to fight together until the finish.
"Now we have a lot of very important games against teams who want to play in next season's Champions League so it is vital to stay focused on these matches and win."