The Owls have lost their last two games but are sixth in the Championship, five points clear of seventh-placed Fulham.
"I don't think the genuine fans of Sheffield Wednesday have Twitter," he told BBC Radio Sheffield.
"Usually the people who have social media use it to talk bad things and be negative."
He continued: "I have absolute confidence that 95% of the fans of Sheffield Wednesday do not think like this.
"I sometimes receive messages from people who are fans telling me not to listen to the moaners on social media."
Carvalhal, who said the club is having one of the best seasons in its 150-year history, took over at Hillsborough in June 2015 and led them to the Championship play-off final last season, where they lost to Hull City.
Meanwhile, the Portuguese has backed striker Jordan Rhodes to rediscover his best form.
The on-loan Middlesbrough man has scored just once in six appearances for the Owls since joining on transfer deadline day and missed a penalty in Saturday's 1-0 defeat by Leeds United.
"He was not playing when he came here and now he has played six games in a row. He was completely exhausted on Saturday so we had to take him off," Carvalhal added.
"Now he has had time to breathe and train he will perform better than in previous games. There's no question he will do better for us."
Sheffield Wednesday boss Carlos Carvalhal does not think people who criticise the club on social media are actually fans of the team.