Spurs won Saturday's early kickoff 2-0 thanks to goals from Brennan Johnson and summer signing Joao Palhinha at the Etihad.
Afterwards, Frank said of Palhinha: "We had a lot of questions about transfers in the press conference yesterday but we did sign two very good players, two top players in (Mohammed) Kudus and Palhinha.
"Today Palhinha, wow, sometimes you just need to get your confidence and I still don't think he's fully fit yet."
Asked about adding to Palhinha and Kudus, Frank also said: "It's extremely important for a couple of things that we've got a good group of players, quality players that I'm very pleased with.
"Can we improve it? Perfect (if we can)."
Moving onto the performance, Frank says the players left him feeling "very proud".
He said, "Extremely proud of the players' performance. I think it was an exceptionally good performance. I think the first 35 minutes, we know a couple of things, we know it's always difficult to play against City. Here at the Etihad it's even more difficult.
"The first 35 minutes I thought was fairly even, but with City on top, I think they were more on top than us. There was a big mentality shift in terms of staying in the game and keep doing what we wanted to do, scoring a great goal. Maybe that changed a little bit of momentum, but we definitely stayed on top and went 2-0."
Pressing worked
As counterpart Pep Guardiola said in his post-match presser, Frank highlighted the impact of the pressing of his players on the day.
He said, "Second half, I think we were very good. The big spell where we could think that they would put pressure on us, I think we were very aggressive in the high pressure, that we were very front-footed, with the mindset to constantly go for the 3-0 goal.
"And then, then I must say that the clean sheet makes me very happy. It's a big thing we've been working on, not on clean sheets as that's easier said than done, but on the defensive side of the game, high pressure, middle block, low block, defend the box mentality, blocking shots, everything.
"Because if you get clean sheets you're closer to winning a game and also last year we had six clears, so yeah, that's very big for me."