The Premier League champions go into this weekend's clash with Sunderland looking to avoid three defeats on the spin for the first time in 12 years, and the veteran winger cannot put his finger on what is going wrong.
"It hasn't been a great start to the season but the good thing about that is we have plenty of time to turn it around," The Mirror quotes Giggs as saying.
"We know what this club is like, it's ups and downs. We don't get carried away if we're flying and we don't get carried away when we're not playing well.
"I can't put my finger on what has happened. We've just not played as well as we can both individually and as a team."
Giggs went on to say that the retirement of former manager Sir Alex Ferguson is not an acceptable excuse for the team's current plight.
"We're the champions so we showed that quality last year and we have to show it again," he added.
"Sir Alex was a great manager and a great influence on the team and the club. You're going to miss someone like that. But I don't think that's an excuse when individuals aren't playing as well as they can.
"We're not playing well as a team. We haven't got injury problems as we have had in the past. So there's no excuse."
United drew 1-1 with Shakhtar Donetsk in the Champions League midweek.