3.6 Vo-p rated buzzer on 5 V Arduino circuit
This is a magnetic buzzer, so the real concern is current, not voltage (you're nowhere near insulation breakdown).
The current is specified as no more than 100 mA, and the coil resistance is 12 +/- 3 ohms.
Applying ohms law, you can calculate that 5 volts divided by 100 mA gives a minimum resistance of 50 ohms.
At minimum coil resistance, you'd need 50-9 = 41 ohms of series resistance to not violate specifications if the buzzer were permanently driven with 5 volts DC.
In practical terms, if you build the depicted transistor circuit but add say a 47 ohm series resistor between the buzzer/diode and the supply, things should be fine - even if you have a bug in your program which leaves the transistor base permanently driven.
In practice, you can probably use a smaller resistor, on the other hand you may find it's already loud enough (at least if you drive at the resonant frequency) and use a larger one.  Do note that if left with 5 volts applied (which you'd want to avoid, though again it could happen as a bug) this would need to be a half watt resistor.  Make sure when you stop buzzing you leave the base low!
There are more optimal ways to drive this, eg incorporating a capacitor, push/pull drivers, etc but you are probably looking for simplicity.
(Yes, there will be some loss in your transistor, too.  You could in theory increase the base resistor, which would decrease the base current and decrease the collector current which is proportional to that via the transistor's gain, or Beta.  But Beta is variable, so it's going to be a lot simpler to get repeatability by keeping your resistance in an actual resistor, and driving the transistor fully)