Barca had an offer turned down by Chelsea last week for Luiz.
"I would be very happy if David Luiz came to Barcelona," said Alves. "I always want the best for my friends and I recommend them to go to Barcelona whenever the opportunity arises. David is not only a friend, but also has a lot of qualities.
"The problem is I do not think Jose Mourinho will let him join us.
"It would mean that he makes us even stronger. It is incredibly difficult, almost impossible."
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