After finishing seventh in the Premier League last season, United have moved quickly to bolster their squad ahead of the 2014-15 campaign - signing Southampton left-back Luke Shaw and Athletic Bilbao midfielder Ander Herrera for a combined fee of almost £60 million.
Incoming manager Louis van Gaal, who will arrive at Old Trafford after the FIFA World Cup, is also reportedly interested in securing the services of Juventus midfielder Arturo Vidal, while Sporting Lisbon defensive midfielder William Carvalho and Fiorentina winger Juan Cuadrado have been linked.
While Yorke - a winner of three Premier League titles during his time in Manchester - said United's activity in the transfer market was unprecedented, it was necessary on the back of a disappointing season that saw the club fail to qualify for Europe.
"I've never seen Man United aggressively spend money," said the 42-year-old.
"They've always bought a marquee player, we've seen that with Juan Mata at £37m during the season last year and then to already spend £60m on two players, that's very expensive spending for Man United.
"The intentions are really clear that we had a bad season but we're going to compete with whoever is out there.
"With players that we want to get in, we're going to get them and we're going to get them in very quickly so we can have a squad and squad that is ready to be prepared for the season and the future ahead."
The former Trinidad and Tobago captain also threw his support behind Dutchman Van Gaal, who is expected to secure a top-four finish and a return to the UEFA Champions League.
"Van Gaal's record as a manager speaks volumes for himself," Yorke said of the 62-year-old, who has won 19 trophies in three different countries.
"Wherever he's been, to Bayern [Munich], to Barcelona, he's been very successful in whatever he does. Although he doesn't stay regularly long at these football clubs, whenever he's there he's always got success.
"So he's a man with a wealth of experience, he knows how to get the best out of players, we expect that when he comes to Man United, we know we're in a transitional period as a team.
"We had a very difficult time with David Moyes taking over from Alex Ferguson but I'm sure with Van Gaal and his experience, his expertise and having Ryan Giggs as his assistant, I think that Man United will advance to be the force that they once were but again we only just had one bad season in the last 20-odd years."
