The 22-year-old suffered a broken vertebra after taking a knee in the back from Colombia's Juan Zuniga during the Selecao's 2-1 quarter-final win in Fortaleza on Friday evening.
Shortly after the news broke that he would take no further part in the tournament, numerous prominent names in football sent messages to the forward, and Messi was also keen to pass on his best wishes to his Barcelona team-mate."Neymar, I hope you recover soon, buddy!" the Argentinian wrote on his Facebook page.
The former Santos attacker had enjoyed an impressive World Cup prior to his spinal injury, scoring four times for Verde-Amarela, but will now miss his side's semi-final with Germany on Tuesday.
Messi, meanwhile, is set to feature in Argentina's quarter-final clash with Belgium on Saturday as the Albiceleste look to try and become world champions for a third time.