The Magpies suffered a surprise 3-1 defeat at home, but still find themselves on top of the table after matchday 37.
Rafael Benitez's side are now tied with Brighton and Hove Albion, the latter recording a 3-0 home triumph over Derby County on Friday.
“We have to put this game behind us,” Atsu said, as reported by The Chronicle.
“We lost the game too easily and it’s a very disappointing result for us.
“But we have to put it out of our minds and focus on the next game. This is all we can do.
“We have to stay concentrated, though.
“We’re not just playing one game, we need to focus on the next ones coming up. Every game, home or away, matters.
“It’s up to us to make things right, we’re still top of the league and it’s time to stick together."
Newcastle face Birmingham City in their next Championship game on Saturday.
Atsu, on loan from Chelsea, has netted three times in 24 appearances for the Magpies.