Having played a part in every United game this season up until Alexis Sanchez's arrival, Rashford has started just one of the six games since, prompting concerns about his role in the side.
But Neville, speaking on the Soccer Saturday Super 6 Facebook Live, insists the 20-year-old's fluctuation in and out of the side is nothing new for young players, and remains optimistic about the Englishman's future at Old Trafford.
Neville said: "No [It's not a concern]. I think he's had a lot of playing time this season, he's had a lot of minutes on the pitch and up until a few games ago had taken part in every match.
"When you're a young player coming into the team, ultimately you're not all of a sudden going to play every game for the rest of your career. Ryan Giggs did that, but that's an exception.
"When I came into the squad, or David Beckham, or John O'Shea, Wes Brown - there are periods where you are in the side for 10 or so matches, in a great run of form, then you dip a bit, then you are out of the team, then you come back in.
"You have that rest, you experience the game from the touchline, you have that period. In my point of view it's not unusual for any young forward or winger to be in and out of the team, it's absolutely usual. It's what I would have expected.
"If I thought he wasn't in the manager's plans, or wasn't in the frame or in favour, I'd be worried then, but I think Jose Mourinho has proven that he likes Marcus Rashford.
"But just at the moment, with Alexis Sanchez signing, with Anthony Martial doing quite well recently, he has just fallen behind those two slightly."
Since arriving from Arsenal in the January transfer window, Chilean Sanchez has played out wide for United, with Romelu Lukaku remaining in a central role.
Neville believes that Belgian striker Lukaku, who has scored 21 goals in his debut season at United, may be sacrificed to trial Sanchez in a more central role, which could give Rashford an opportunity out wide.
"My views at the moment is that the one person who is under some pressure is Romelu Lukaku, in terms of his form, and also that Sanchez could go up front, because I'm not sure he's suited to the right. That may allow Marcus to come back into the team.
