The Colombia international arrived on a season-long loan deal from Monaco in September, but has scored just four times in 19 appearances across all competitions.
Falcao's latest disappointing display came in United's 3-1 FA Cup fifth round victory at Preston North End on Monday, with Louis Van Gaal's side coming from a goal down to win after Falcao's 60th-minute withdrawal.
But, Saha - who played for United between 2004 and 2008 - has no doubt that Falcao can rediscover the kind of form that made him one of Europe's most-feared frontmen at Atletico Madrid and Porto.
"I have sympathy with Falcao but I have no doubts about him," the Frenchman said.
"I know how hard it is to be a striker. There is always a lot of competition at this club.
"When you are in a club and there are only one or two strikers and you are one who will definitely start it is different. But at United it is not like that. It is a battle.
"Falcao is under pressure because of his contract situation. But he has the quality to do a great job here.
"It is very hard. It is the hardest time in your life. You are a footballer and you want to play and you have to really, really work hard to come back physically right, but also mentally.
"You have to get back the confidence and the linking up with other players. It is really tough.
"You need to work with a team full of confidence. When I was coming back [from injuries] I had team-mates scoring goals every week, so it was easier for me. The pressure wasn't as big."
