The Nerazzurri suffered their first loss of the campaign, a 3-0 reverse at the San Siro against Serie A leaders Roma.
The result dropped Inter to fourth place, seven points behind Roma, heading into the international break.
"This defeat is a lesson for us that perhaps we need to work harder," Moratti said to www.fcinternews.it.
"We also need to understand that when a game becomes difficult we have to make the necessary changes to get back into it.
"In any case, I cannot fault my players because they fought until the end after conceding three goals in the first half.
"We just have to give more in the future."
Inter's next match is at Torino on October 20.