The Barcelona star has come in for criticism from certain sections in his home country for not recreating the sensational form he regularly displays in a Barca shirt.
However, Maradona has leapt to the defence of the four-time Ballon d'Or winner.
"We are watching a truly exceptional player," Maradona told Fox News.
"Every time he goes on to the pitch, he invents a new thing and it is fantastic. I've seen him suffer greatly in Argentina, but now everyone is behind him – even the journalists."
The former Argentina coach also refuted suggestions that Messi cares more about the fortunes of his club side than his national one.
He added: "When we lost to Germany in the last World Cup (2010), we went to the dressing room and the only one you could hear sobbing and crying was Messi.
"He was hurt. He was sad. I'll never forget that."
Messi is currently top of La Liga's goalscoring charts with 35.