City, who earned 198 points over the past two full seasons, lost for the sixth time this campaign and find themselves 22 points behind leaders Liverpool.
Pep Guardiola's side had 18 shots to Spurs' five at the Tottenham Hotspur stadium and enjoyed 68% possession while Ilkay Gundogan missed a penalty before goals from Steven Bergwijn an Son Heung-Min secured victory for the home side. And Fernandinho has called on his side to be more efficient in front of goal.
"It's a bit difficult," the Brazil international said when asked to explain the loss. "It's a painful defeat, especially given how we played.
"We continue to create chances but are not clinical enough. We missed another penalty, continued to miss chances and then they scored twice.
"This has been our season. It's clear that conversations are important because we can't let things go on like this."
City are two points ahead of third-place Leicester, while Tottenham, in fifth, are 14 points behind. However, despite the gap, Fernandinho said City are looking over their shoulder rather than up at Liverpool.
"Liverpool have practically won the league now, with how far ahead they are," he added. "We need to be careful because from now until the end of the season, we could lose more points and, subsequently, our [second] place in the table.
"We could even finish outside the Champions League places. I hope next week we get a positive reaction from our fans at home because it is more than needed."