The loss - only our third in the last 24 matches in the Premier League - means our lead over the Gunners and Chelsea has been cut to seven points with 12 games remaining.
"We want that third spot," said Harry. "That is what we are after.
"I have said all along we have got to make Champions League football.
"It is not going to be easy. Arsenal and Chelsea are strong teams and we haven't finished above them for a long time, but this is our best chance, so we have to make sure we pick ourselves up and be ready for the next game.
"We've a tough run, United, Everton away, Chelsea away so we have to make sure we're ready. It will be a big game at home to United.
"We are still seven points clear and if we can make that third place it will be a great season for us."