Inter were stunned 2-0 as Flu struck through German Cano and Hercules.
Chivu said afterwards: "We lacked brilliance and freshness, the approach was not good, not from a team that wanted to give everything it had. As I also said in the cooling break we were presumptuous, looking for the good when we could have attacked the line more easily.
"But today we were like this, with this energy: we tried to turn the game around and we were also unlucky between the post and a clear situation for (Stefan) De Vrij. We conceded two goals with three shots on goal.
"I always take the full part of the glass, if you only look at the negative you get a headache. The task is to start again from these three weeks and plan the new season and the objectives."
I was more delicate
On captain Lautaro Martinez's harsh words for Inter, the coach also said: "We are winners and we have this competitiveness that brings out pride and character, we try to transmit them to everyone.
"If I'm not mistaken, I also said that we all need to stay rowing in the same direction on the boat. I was more delicate, perhaps, he came in with a strong leg.
"But this is because the club wants to redeem a year that was not easy to manage and that prepares the future with determination."