United have made their worst start to a league season since 1989 under new manager David Moyes, with last weekend's defeat to West Bromwich Albion their third in six Premier League games.
Buttner has called for Red Devils fans to trust an experienced squad to improve in the next few games, starting at Shakhtar Donetsk on Wednesday night in the Champions League.
He told The Guardian: "We have lost three games but we have to focus in every game and we have to fight in every game to win.
"We are not in crisis. Of course the crowd wants to see Manchester United winning, and the players as well. If we lose we aren't happy, we want to win as well and we have to fight in every game to win.
"This season starts now and we can win many games. You have to trust the players and everyone. I think we can do this as a team and we're going to win games, I'm sure."
The 24-year-old has started United's last two games, with his first involvement under Moyes coming in last week's League Cup win over Liverpool.