Ronaldo has agreed to return to United on a two-year contract after the club struck a deal to buy him from Juventus.
United have agreed to pay Juventus an initial £12.85million (€15m) with another £6.86m (€8m) in add-ons for the 36-year-old forward.
That was announced on Friday afternoon, just hours after he appeared poised to join Manchester City.
City had been strongly linked with a move for Ronaldo after failing to land Harry Kane from Tottenham and seemed to be his most likely destination.
However, United pounced, with Ole Gunnar Solskjaer mobilising Sir Alex Ferguson and Rio Ferdinand, amongst others, to convince Ronaldo to return to the club he represented between 2003 and 2009.
That undoubtedly came as a blow to City, but Guardiola was tight-lipped when asked about the dramatic events surrounding Ronaldo ahead of Saturday’s match against Arsenal.
“I don’t think frustrated is the right word,” he told BT Sport.
“We have an exceptional squad and we have improved to have the best possible team to compete.
“It’s good that a player like Cristiano Ronaldo is back in England for the Premier League and it’s good news.”
Less than 24 earlier, Guardiola had offered quite a different take when asked by signing Ronaldo in his pre-match press conference.
“Cristiano is a Juventus player and I can’t say anything else,” he said.
“All I can say in these three, four days left of the transfer window anything can happen.”
When pressed further, he added: “I say the same: Cristiano will decide where he wants to play, not Manchester City, not myself. There are many things that are far away.”
Ultimately Guardiola was proven right, with Ronaldo opting to return to Old Trafford, rather than taint his reputation with the club by joining their rivals.
Ronaldo will undertake a medical in Portugal ahead of his country’s upcoming internationals before joining his new team-mates after the international break.
He could then make his first appearance for the club in 12 years when United host Newcastle in the Premier League on September 12.
Gary Neville believes the signing could make all the difference in the title race this season.
“Ronaldo will be coming to win trophies, personal accolades, set the Premier League on fire,” he said on the Sky Sports Transfer show.
“It is a different Ronaldo, everyone expected that. But he is a number nine, someone who still has that burst over short distances, he makes great runs inside the box, has anticipation of where the ball’s going to drop, and he gives United something they need.”
He added: “I said the other day United should be in for Kane if he was available, or Haaland.
“These types of player, to get above Manchester City and Chelsea, they’re going to have to do something big, and this could give them a temporary shot in the arm to get them right up there this year.”