The former Barca coach and captain says he hopes Laporta is patient with new coach Hansi Flick.
He said, "I hope Laporta is finally patient with his coach. If you don't feel the support of the president you are lost.
"In many things Real Madrid is superior to Barça. I know that Barça has a lot of young people like Lamine, Pedri or Gavi, but you need people like Mbappé who make a difference in every way.
"If you don't have this type of player or someone like Messi ...
"Lamine at his age is impressive, but you have to give him time and peace of mind. Messi, there is only one in the world, we will not see another in the future."
Koeman also said: "I understand the interest in Nico (Williams, Athletic Bilbao) because he is a great player. I don't know if they are rumours or if they are intentions to think that they can fight for this type of player. In recent years, Barça's problem has been that Messi is out, I am out, Xavi is out… I think it is best to respect the club's legends.
"That is much more important than fighting for a player. Barça has to be at the top of everything and lately in recent years it is not there to compete. It seems that the club legends do not paint anything for the board."