The 23-year-old, who has netted 14 times in his first season at Anfield, had been included in his country's squad for this month's friendlies against Japan and South Korea.
But the Reds confirmed he will undergo treatment at the club instead. Liverpool did not specify the nature of the injury but it is understood to be related to a cut ankle sustained during Wednesday night's Champions League defeat by Real Madrid.
Meanwhile, the club's former midfielder Lucas Leiva has announced his retirement at the age of 36.
The Brazilian, who was a popular player during his decade on Merseyside, took a break from the game after a heart defect came to light in December.
After further tests, he has now decided to end his playing days for good.
He said on social media: "The day has come to say goodbye to the field. I confess that it came from greater forces, but I look back and can only be thankful for the career I built. In 2007 I transferred to the giant Liverpool, which was part of my life for 10 years. It is with great pride that I can say that today Liverpool is my home. I'm proud to be an English citizen and along with my family; I'm Scouser!"
The former Brazil international's career had gone full circle following a five-year spell with Lazio, returning to Gremio last summer - the team he left to join Liverpool in 2007.