Per ESPN, he said: "Of course, the Premier League is an unbelievable league. You never know in football what can happen, so right now, I'm focused with Dortmund, and yeah, that's that."
The 19-year-old has been linked with United and Liverpool in the past and said of the transfer window:
"[The transfer window] was definitely kind of a whirlwind. Every day, you hear something different in the media or whatever, something like that, but now that it's over, our team has been having kind of a rough go of things lately. So many different coaches in the last few months, but yeah, right now, we've just got to turn that around and focus on ourselves."
The teenager has made 81 appearances for Dortmund, producing 11 goals and 15 assists.
Pulisic has also made 20 appearances for the United States' men's national team and scored nine goals, a demonstration of the exceptional promise he represents.
The forward confirmed he was a boyhood supporter of the Red Devils:
Though United have just added Alexis Sanchez to their attacking lineup, they're likely well aware of Pulisic's precocious talent and would relish the prospect of recruiting him—particularly if it involved beating Liverpool to his signature.
The American can operate on either flank or in the centre, and he possesses searing pace and excellent close control.
Such qualities allow him to cause defenders all manner of problems, and he also boasts a maturity to his game that belies his tender years.
Football writer Jack Grimse shared an example of a recent performance:
Pulisic still has room to improve further in order to offer an even greater goal threat, but what he's achieved at his age makes him one of world football's most exciting young talents.
It will hardly be surprising if a Premier League move is in his future, but for the time being, he's doing the right thing and focusing on his current club.