Arsenal slumped to a 2-1 defeat in Sunday's north London derby against Tottenham at White Hart Lane, where Kyle Walker drilled in what proved to be the winner from 30 yards.
Song had been pushed back into a central defensive role because of an injury crisis which worsened when Bacary Sagna was later ruled out until the new year with a broken leg sustained during the game.
Following a fourth Barclays Premier League defeat of the season, Arsene Wenger's men are closer to the relegation zone than the Champions League places, which for Cameroon international Song is an uncomfortable position.
He told Arsenal Player: "We need to just keep going. We can't lose games like this, it is not normal. We are not allowed to do it, for the fans and for everyone who loves Arsenal.
"We need to learn from this one for the future because we are not in a good situation at the moment.
"When everybody comes back we will feel very good and strong.
"We need to keep our heads up and try to push ourselves to learn and give the best for the future."
Song added: "Arsenal being in this position is not normal. We now need to show something very good, not just for the fans, but for us as well.
"Arsenal always fight for the first place, the top places. Now we are not in a good situation."
The Gunners are next in action against Sunderland on October 16 and Song is expecting a response.
He added: "It is very important for us to come back after the [international] break with a winning mentality.
"We want to show that we are not down, we are here and we can do something good.
"The next five games are very important for us.
"We need to win every single one to come back and show the fans that we are ready and that we are to fight for the league."