The Royal Blues created enough chances in Romania to start their Europa League group stage campaign with a win, but neither Raul nor Klaas Jan Huntelaar was able to find the back of the net.
Rangnick said: "Primarily, our defensive performance was satisfactory because we did not let our opponents have a single chance.
"Unfortunately, we failed to turn our dominance into goals.
"Overall, though, we can live with this result. The important thing was that we did not concede, and never looked like conceding."
Rangnick was therefore optimistic about his side's chances in Europe this season.
"If we can succeed in getting a draw away from home against Romania's strongest side, then we can also win this group," he added.