The Cottagers sit 17th in the Premier League after taking just two wins from from their first seven games and speculation surrounds the Dutchman's future at the club, though the Swiss feels that the criticism is unmerited.
"I understand the frustration from the fans but the manager doesn't deserve [the criticism]," Kasami told The Fulham Chronicle.
|10/3||Fulham are 10/3 with Bet365 to be relegated from the Premier League
The midfielder has made eight appearances for Fulham in all competitions so far this season and secured a place in the Switzerland squad for their World Cup qualifiers with Albania and Slovenia on the back of his strong individual start.
"I'm one of the youngest in the team and I try to show every week what I can do," Kasami enthused. "I'm very pleased with this season because I've been playing a lot and showed a lot of people that I can be an important player for Fulham.
"I'm the captain of the [Switzerland] Under-21s but the first-team coach told me I'm a very important player once they qualify for the World Cup.
"For now my job is to do well at Fulham and the rest will come."