Former playmaker Andrea Pirlo joined the criticism after Italy's 1-0 defeat to Sweden on Friday left the four-times champions on the brink of missing out on the World Cup finals for the first time in 60 years.
"Italy looked like a scared team that was playing for a 0-0 draw. In Europe, that is not enough," Pirlo told Sky Sport Italia.
The 38-year-old also had little sympathy for Ventura's complaints about the referee.
"It's a red herring," he said. "Playing in Europe is not like in Italy, where you get a free kick for even the slightest contact. In these matches you need to be above all that and give 100 per cent; it's in these matches that you see the real players.
"San Siro will make its presence felt [in the return leg] but I've never seen a goal scored from the stands," he said.