Only Handanovic and assistant manager Cristian Stellini went to the media zone after seeing Lautaro Martinez sent off.
“There is always irritation when we don't win, as we always want to win, but didn't make the most of our chances," Handanovic told Sky Sport Italia.
“We certainly didn't drop points because of the referee today. We just complained because he didn't give free kicks to our forwards and he did to the Cagliari ones.
“We're not blaming the referee for our draw. We must learn to finish games off earlier, as then we wouldn't even need to be talking about these incidents.
“There is definitely something missing from the team because we keep conceding second half goals, but it's not just the defence. We all lack concentration and don't kill games off when we have the chance. Some errors are avoidable and we must take responsibility."