The 34-year-old still has two years remaining on his Barcelona deal, but Petrescu has suggested that an agreement is already in place over a deal to bring him to Qatar.
"Xavi has signed a pre-contract with Al-Arabi. It is likely that he has offers from other clubs too," the 46-year-old told digisport.
"We are in direct contact with the player. He is currently in Brazil focusing on his job with the national team.
"I talked to him on the phone and I appreciate that he's an extraordinary man. If Xavi comes here, we'll be able to attract bigger names but I'm not prepared to disclose these names now."
Xavi is expected to be in the Spain side to face Chile on Wednesday night.