United finished second in the Premier League and runners-up in the FA Cup, but some sections of the support are growing dissatisfied at Mourinho’s tactics.
And Sharpe, who played for Alex Ferguson’s United side from 1988 to 1996, believes tensions will only rise if Mourinho does not change his approach.
“For me it was a pretty disappointing season and not entertaining enough,” Sharpe said. “There are clubs with certain identities and United have never been a 1-0 team that sits back and rests on its laurels.
“You’ve got the blue side of Manchester under Pep (Guardiola), you’ve got Jurgen Klopp at Liverpool playing some of the best football in the league and United are playing slow, pragmatic, boring and even dated football.”
“Maybe it’s time Mourinho reassess things tactically. He’s been one of the most successful managers in the game over 10-12 years, trophies everywhere he’s gone, so I can understand him saying, ‘I’m doing it my way’.
“But times have changed and if it doesn’t start well next season he could find himself under pressure from the fans.”
Liverpool may have fallen short in the Champions League final, not to mention six points behind United in the table, but Sharpe thinks fellow United fans will be envious of the fare on offer at Anfield.
“Who wouldn’t be?” he said. “Liverpool play on the front foot, they’re entertaining, they’re exciting and they score a load of goals.
“The play like we used to. They’re not a team to settle on a 1-0 scoreline, they chase games.”
Meanwhile, United are closing in on a deal for highly-rated Porto full-back Diogo Dalot.
It is understood there is a good chance of a deal being reached between United and Mourinho’s former club instead of using the €20m release clause that soon becomes active.
Dalot, a right-back capable playing on the left, has only made a handful of senior appearances for Porto, but is considered a huge talent and has attracted interest from many teams across Europe.
The teenager could be joined at Old Trafford by Shakhtar Donetsk’s Brazilian midfielder Fred, while Tottenham centre-back Toby Alderweireld has been linked with a move.
Long-time target Gareth Bale’s clear agitation at Real Madrid will see his future monitored by United, while several players could exit this summer.
Speculation continues over the future of Daley Blind, Anthony Martial, Matteo Darmian and Luke Shaw, while divisive midfielder Marouane Fellaini’s contract expires this summer.