Arduino AC low voltage to GPIO
No, it is not safe. You must limit the input to your arduino to 0..5V DC.

In your shoes I would probably use a suitable (AC!) optocoupler like a PC814. Connect the LEDs of the PC814 to your AC source with a suitable resistor (1k, for a start), in paralel with the bell. The PC814 output transistor can be connected to your Arduino input, maybe with a pullup resistor (again, try 1k).