Martial picked up a foot injury in France’s friendly against England this week and left Wembley on crutches.
However, the striker’s wife later appeared to confirm on Instagram that Martial is not injured, although she removed the message shortly afterwards.
Rooney admitted he is worried about Martial’s fitness ahead of the game against Watford this weekend.
“From a personal point of view, and from Manchester United’s point of view, I hope he is okay. I will try to ring him,” Rooney said.
Martial has been a key player for United since his summer move from Monaco.
His absence would leave Louis van Gaal short of options up top, as Rooney is the only other real out-and-out striker. Van Gaal will likely reveal how severe Martial’s injury is in his press conference on Friday.