It's only been 2 weeks...
I'd argue that you don't have to mention this job at all. When asked why you're job searching you can explain why you left your previous position.
If for any reason you can't omit a job from your work history no matter how short (locale, the type of job you're applying for, etc.), you can be honest without going into details:
I'm leaving my current job because the position changed significantly after I started.
This is true: you took the job because you were expecting a raise and now that raise isn't going to happen. But you don't have to mention that the significant change was about compensation.
This is a common enough situation that they ought not to press you further.