Ashley Young fired Inter ahead before a Ciro Immobile penalty and Sergej Milinkovic-Savic's strike secured the win for the Romans.
“I think it was a good performance, it's the result I didn't like and the way we conceded the two goals, as we gifted them to Lazio," the coach told Sky Sport Italia.
“We were not impeccable, but inevitably in these big games, the details become decisive and the margin of error becomes reduced. It's part of a growth process, there was some naivete and these lads must try to be more relaxed in these situations.
“We were too soft on the two goals. We had other situations this season where we had taken the lead and threw points away, for example also Barcelona and Borussia Dortmund, games we had in our grasp and ended up losing.
“As I said, this is a growth process and we have to go through it so that we can face every situation the right way. Straight after the restart, it was as if we were scared. That has to improve.
“The lads worked hard and I thank them for that. We are trying to irritate the teams at the top, it was a 'head-to-head' with Lazio and we ought to be proud to have been in this situation in the first place. At the same time, we must improve if we are to continue causing problems up there."