If I run an ATMEGA328P on 3.3V will the built-in I2C also be 3.3v

I know that may sound like a stupid ?,,,but,,,just making sure.
I have a board(SI4707 breakout board) that I will be interfacing that runs on 3.3v and using I2C ...
I don't want to buy a level-shifter.
Trip - KT4WO
PS--I have etched a simple board for the chip...kinda a UNO without the extras... Just a 16Mhz Xtal and a few caps.
It will be running "stand-alone" controlling the WX chip and an audio amp(LM386).