The 24-year-old, who missed the start of the season as he recovered from shoulder surgery, was only a second-half substitute against Manchester City in the Manchester derby on Saturday, having struggled with illness in the build-up to the contest.
Rashford had been due to link up with the England squad for their November internationals, but a statement on Man United's official website revealed that he would be remaining with his club.
"Marcus Rashford will remain with Manchester United in order to concentrate on regaining full fitness as England face their final two World Cup qualifiers," read the statement.
"Our number 10 was cleared to be on the bench for the Manchester derby and came on in the second half of the 2-0 loss, replacing Mason Greenwood after 66 minutes. Yet he remains short of full fitness as he has been building up his game-time for United and has still to complete a full 90 minutes since the enforced lay-off."
Luke Shaw, meanwhile, is also a doubt for England's two matches, as the Red Devils defender was forced off against Man City on Saturday with a head injury. body check tags ::