The 26-year-old's future with the Selecao has recently been in doubt after he missed friendlies against Russia and Italy in March.
Brazilian officials believed that his absence was due to a lack of commitment, but Chelsea have now confirmed that he was unable to play because of an injury.
"Contrary to media reports, Chelsea Football Club can confirm that Ramires was not available to play for Brazil in friendly matches against Russia and Italy in March of this year due to injury," read an official statement from the Blues.
"The left adductor muscle injury was confirmed following an MRI scan and he underwent treatment at Chelsea FC's medical department from March 17 to March 28.
"Throughout this time information was relayed to the Brazilian national team doctor in the usual way and the treatment was agreed between the club and national team.
"However, Chelsea FC would like to apologise that it was not made clear when Ramires would be able to report back to the national squad."
Ramires has won 34 caps for Brazil since making his debut in 2009.