Pulisic sustained the problem during the weekend win against Crystal Palace and will play no part in his country's games against Canada on Saturday or Cuba the following Wednesday.
The extent of the damage and how long it will keep him out for has not been revealed, but USA head coach Gregg Berhalter has confirmed he will play no part during the international fixtures as they are not prepared to gamble on the player's fitness.
"Christian is officially at this stage ruled out," Berhalter told a press conference. "We just got that information.
"This was a collaborative decision with the club, looking after the best interest of the player.
"These decisions are always difficult because this group and the coaching staff want nothing more than to have Christian here, but it was a risk we weren't willing to take at this time."
Pulisic was signed from Borussia Dortmund in January but only linked up with the rest of the Chelsea side in the summer, and has taken time to adapt.
The forward has gone on to play a key role this season for Chelsea, who have won their last six Premier League matches to climb up to third in the table.
The 21-year-old has established himself in Frank Lampard's starting line-up and has scored five goals in his last three league games, including a hat-trick in the 4-2 win at Burnley.
Chelsea are sure to give an update on the injury at some point in the near future, and Chelsea fans will be hoping it is good news.
The USA will play Canada and Cuba in the latest round of their CONCACAF Nations League group matches.
Frank Lampard's side return to action on Saturday November 23 when they take on Manchester City at the Etihad Stadium and will be hoping Pulisic is fit enough to play.