Inter fell 2-0 on Saturday.
"Sometimes you don't manage to do what you want to do," Handanovic said
“In the second half we came back out to do well and push hard, but they defended well."
Handanovic stressed the need to Luciano Spalletti's team to look forward as they continue to battle for Champions League qualification.
“We need to rediscover our nervous energy, turn the page and face the upcoming matches with enthusiasm.
“It's a bit of everything that is going wrong. I don't believe in coincidence – things went badly here.
“There are no excuses, we will fight to the end against everyone.
“I have played in matches like this a lot – with an opposition who have two shots and score two goals.
“We need to move forward, there are still a lot of battles ahead."