Higuain appeared to trip home defender Kamil Glik before racing in to score and afterwards the Argentina international admitted there had been contact.
Ventura was loathe to discuss the incident, saying only he had been left embarrassed and that Torino had been on the wrong end of such decisions too often this season.
"I don't want to talk about it," he told Sky Sport Italia.
"You have to accept the on-field decisions, but we've lost 10 points this way.
"The incidents are obvious, it's embarrassing. I'm just going to concentrate on talking about the game and wait for this season to end as quickly as possible.
"We hit the woodwork twice, missed seven scoring chances and it is a shocking injustice to have lost this game."
Higuain admitted contact with Glik, but denied it was necessarily a foul.
"On the contact with Glik I was running very quickly and so was he," he said.
"I can only celebrate the goal. It was a very difficult match, but they are extremely important points and I am happy because we got closer to Roma."
Napoli are three points behind Roma in the chase for the second direct Champions League berth.
The capital club beat Udinese 3-2 on Monday night and have a game in hand.