The 21-year-old was rumoured to have attracted interest from Inter Milan and though his agent has denied receiving any contact from the Serie A giants, he says he told United to approach Bologna directly regarding the highly-rated Algeria international.
George Atangana says Taider has not expressed a desire to leave Bologna but he wants the club to increase the former France Youth international's salary to reflect the level of interest his client is attracting.
The agent told Corriere di Bologna: "The boy is not happy and I hope that Bologna's leaders call us quickly.
"Inter? I have not even talked with them. I heard from Manchester United and I told them to contact the club directly for any negotiation.
"Saphir would like to be treated with respect. If Bologna value him at £15.6million, he deserves more than the £217,000 per season he earns.
"Saphir loves the shirt he wears, and he will continue to work for that. But if Manchester United are interested in one of your players and you want to keep him, you should make him happy and give him what he deserves."