Having taken over from Sir Alex Ferguson, who retired in the summer, Moyes has seen United crash out of both the FA Cup and League Cup as well as slip to seventh in the Premier League table and find themselves 14 points adrift of league leaders Arsenal.
"I am not going to accept it," Moyes told reporters. "I am disappointed we are not in a much stronger position. I am disappointed with how we have played.
"I, ultimately, take the wrap for that. But what I will do is make it right. I am going to get better players in.
"Unfortunately, I don't think there will be more in January. But it will change."