United's 2014-15 Premier League season hit a new low on Sunday, when they surrendered a two-goal lead to lose 5-3 at promoted Leicester City.
It left Louis van Gaal's men languishing in 12th position, with just one win from five fixtures.
However, captain Rooney fired back at United's critics on Tuesday, believing there is enough quality to enjoy a change in fortunes.
"There seems to be a lot of people who have written us off because of Sunday's result but I don't see it that way," Rooney wrote on his official Facebook page.
"When I look around our dressing room and see the quality we have and the manager's unbelievable attention to detail I have no doubts this team will be successful."
United play host to West Ham at Old Trafford on Saturday.
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