The departing PSG star is in talks about re-signing for the Blaugrana.
Xavi told Mundo Deportivo: "He has the doors open here, I am the coach and I know that he will help us if he decides to come, but in the end I think we have to leave him a little alone.
"He ends his contract with PSG and then he has earned all the right in the world to say where his career ends. If he comes to Barça, what all the culés want, especially the coach, he has the doors open, I am convinced that he will go well.
"For me there are no doubts. If Messi decides to come, he has the doors open at the football level. I know he will help us. There is no doubt. From there, the contractual issue is no longer my concern.
"That next week he will make a decision and you have to leave him alone. In the end, if we talk about Messi every day, I think he doesn't add up either. In the end he will decide next week and now there are 200 hypotheses. In the end, he will decide his future and here he has the doors open, there is no more debate."