The result leaves City 11 points behind leaders Liverpool.
Guardiola said: "We have to accept it, work on strengths and learn from it.
"It's tough but we have just two days to recover.
"In good moments, be calm.
"In bad moments, live these kind of moments."
When asked to compare this term's performance with last season, Guardiola said: "Last season we played bad, we played poorer than today, we did everything to win the game and the guys responded perfectly," he said.
"We played at a good level, defending set-pieces and everything, we move the ball well, we found spaces outside, especially with Benjamin [Mendy], we arrive in front of goal many, many times but we couldn't score."