Is it allowed to stop and restore I2C transmission?
The minimum bus speed for all I2C modes is 0Hz. This means that it is valid in the I2C specification to stop pulsing the clock (static operation).

However, this does not mean that slaves must also support static operation; they may have internal timeouts which may elapse before communications is resumed. Always check the datasheet of any I2C slave devices to verify that they support static operation.