The Serie A giants have regularly been linked with an audacious move for the six-time Ballon d'Or winner this summer amid reports that Messi is unhappy at Barcelona.
The 33-year-old is in the final year of his contract at Camp Nou, and speculation over his future was fuelled further this week when his image was projected onto Milan's cathedral.
However, Marotta has played down speculation that such a deal could take place, despite admitting his desire to see it happen both for the club and for Serie A as a whole.
"Messi on the cathedral? It wasn't my idea. It reminds me of football from the past with such situations. We are talking about an icon, a great player, a desire that everyone has," Marotta told Sky Sport Italia.
"[It would be] extraordinary to see such a champion at Inter. It's fantasy football, a utopian situation. Our football [in Italy] needs a lift. Champions raise the value of the Italian brand and football.
"If we could consider ours to be a championship in which the great champions come and stay, it would be better. No Italian team is capable of carrying out such an operation unless extraordinary factors arise related to the shareholders, and therefore the actual owners.
"Let's not forget that we must respect FFP [Financial Fair Play]. This year, COVID-19 has ensured that there is some flexibility, but afterwards the rules will have to be respected."
Messi has spent his entire career with Barcelona so far, scoring 633 goals in 729 games for the club across all competitions.