By FOX Sports Staff
The Barca star had grown up being influenced by Martino who currently holds the record for most individual appearances at Newell's Old Boys.
Messi, who featured for the Argentinean side during his youth career, had intimated that Martino would be an appropriate choice to succeed Tito Vilanova, after the 44-year-old had to step down from the Barcelona helm due to a cancer relaps.
The move did come as a surprise as Barcelona were linked with a host of famous names in Europe with the likes of Michel Laudrup, Andre Villas-Boas and Guus Hiddink being mentioned as possible candidates for the vacant managerial position.
The forward issued a firm rebuttal to such rumours, though, following Barcelona's 2-0 friendly defeat to Bayern Munich on Wednesday night.
He said: "I don't have anything to do with the signing of Martino and I have nothing to explain. It's [Barca president Sandro] Rosell and the club's thing."
"At that time, I said that he looked like a good coach, but I have nothing to explain.
"I don't know him personally and have never seen him or Luis Enrique, who was also linked.
"He seems to be a good signing as he has demonstrated with Newell's and Paraguay that he is capable. Hopefully he'll do well here.
"After Tito's departure, we must begin again. It will be a hard season for us."
Martino, who led Newell's Old Boys to the Argentinian Clausura title last season and guided Paraguay to the quarter-finals of the 2010 World Cup and final of the 2011 Copa America, has agreed a two-year contract with Barca and will be presented on Friday lunchtime.