The 34-year-old's current deal at Old Trafford runs out at the end of this season, with the former England international free to negotiate terms with other clubs.
Ferdinand has reportedly attracted interest from the MLS and Far East but Sir Alex is confident he will sign a new deal with the Red Devils.
"We are not panicking about that," the Scot told reporters.
"I don't think Rio wants to leave and, as I have said before, he can play on.
"I don't think he has the same issue with his back that he had a couple of years ago. It is manageable now.
"There is no way you would be expecting him to play every four days right through a season anyway.
"Getting rest at the right time definitely helps him and he does a lot of work on his pre-match preparation now, with yoga and a lot of other things to help him sustain his playing time."The United defender has been in and out of the team this season, making 18 appearances in all competitions for the Red Devils so far.