Sandro resigned as Barcelona president after he was accused of misappropriation of funds from the €57m signing of Neymar from Santos in 2013.
Neymar eventually left the Catalans for the French Ligue 1 side in a world-record of €222 million after four seasons at Camp Nou, but has been linked with a move back to Barcelona since the beginning of last summer.
Barcelona are desperate to find a long-term replacement for Luis Suarez and are said to be mulling over reinforcing their attacking options with likes of Lautaro Martinez and Timo Werner.
The Spanish business mogul has urged the Spanish champions to re-sign the Brazilian and believes the 28-year-old is the second best footballer in the world.
Despite admitting Neymar is talented, the Spaniard said he would have signed the Sao Paulo-born star with two contracts; one would be sports and the other one to check his abhorrent behaviour.
"If I were the president of Barca, I would try to sign Neymar," Rosell told COPE and Radio Marca.
"He is the second-best player in the world after Messi and fits perfectly into the philosophy of the club.
"But with experience, i would sign him with two contracts, one sports and the other behavioural."
Neymar played 186 times for Barcelona and scored 105 goals, winning two La Liga titles and one Champions league in the process.