The 26-year-old was unhappy with the way his side began the game against Cagliari and urged his team-mates to improve against the struggling sides in Serie A
Walter Mazzarri's men were trailing 1-0 at the break at San Siro, with Mauricio Pinilla converting from the penalty spot in the 40th minute.
The hosts ensured a share of the spoils when Rolando scored his third goal of the campaign shortly after the break, but Inter were unable to find a winning goal.
Kuzmanovic revealed his disappointment at having dropped points against a side that are now just five points above the relegation zone and said there was no excuse for the lethargic first half.
"As far as the game went, we are not happy with a draw at home," he told the club's official website. "We lost two points. It hurts to draw against the ‘small’ teams.
"We ran into some problems and despite the chances we had we weren't able to take full points.
"I couldn't tell you why we played poorly in the first half. We always have to be careful defending against counter-attacks.
"We had our chances but we just couldn't turn them into goals. Our rhythm was a bit slow in the first half. We should have had the same attitude we showed in the second half for the entire game."
Inter almost had a winner in the closing stages when substitute Mauro Icardi crashed a header off the crossbar and had claims for a penalty when he was impeded in the follow up.
Kuzmanovic says he is certain a spot-kick should have been awarded, adding: "The penalty claim on Icardi? It should have been given in my opinion."