Macario, 23, has not played since suffering the injury in French club Lyon's final game of last season almost a year ago.
Although she has returned to training, the end of Lyon's season on Saturday will leave her unable to get competitive minutes before USWNT coach Vlatko Andonovski announces his roster for the World Cup by July 10. The tournament in Australia and New Zealand is set to begin on July 20, with the U.S. playing its opener against Vietnam a day later.
"While I'm excited and super optimistic about my future as a footballer, I'm sad to share that I won't be physically ready for selection to our U.S. World Cup team," Macario posted on social media.
"The desire to return to play for my country has driven my training and fueled my everyday life. However, what's most important right now is my mental health and getting fit and ready for my next club season.
"I am eternally grateful to Aspetar Orthopedic and Sports Medicine Hospital for always supporting me and guiding me in my rehab. And to U.S. Soccer and Vlatko Andonovski for prioritizing my long-term health over any individual and collective ambitions.
"I'll be cheering hard for my teammates at the World Cup, and I look forward to dedicating myself to fight to earn a spot for what I hope will be a long future on the U.S. national team."
Macario, who has been linked with a move to WSL side Chelsea, has eight goals and two assists in 17 appearances for the U.S. and had been a key figure for the team. She was named the MVP of the SheBelieves Cup in February after scoring two goals in the team's final game against Iceland.