The La Liga giants have agreed a deal with Messi which would tie him down until 2021 after a new deal was announced in July, with his previous contract due to expire in 2018.
However, the formal signing of the contract, which was expected to soon follow, has still yet to be signed by the Argentinian, leading to speculation over his future.
Barcelona president Josep Maria Bartomeu claimed earlier in the week that Messi's father Jorge had already signed the deal, making the contract valid.
Nevertheless the deal still needs Messi's signature for the contract to be officially completed, something that Fernandez expects to happen soon:
"I point to our president's words.
Lionel Messi:— SPORF (@Sporf) September 9, 2017
⚽️ Goals: 571
From another planet pic.twitter.com/WqaPzTMmH7
Messi delivered again for Barcelona on Saturday, scoring a hat-trick to lead Ernesto Valverde's men to a 5-0 thrashing of Espanyol and putting them four points clear of Real Madrid so early in the season.
Fernandez lauded Barca's Argentinian talisman for his performance, especially after coming back from the international break.
"He's come back from international duty, after a lot of travel and two tough games," said Fernandez.
"He is capable of changing a game at any moment and the difficult thing he manages is to maintain that rhythm."
Messi appears set for a long-term Barca stay, despite recent links with Manchester City. However, Iniesta's future is less certain, with the 33-year-old
"What we want is that Andres is here for many more years and that he ends his career here," claimed Fernandez.
"I'm convinced that will happen."