FFT of real signal with nonuniform sampling

Hi all, I have just acquired data from a JR3 force sensor. Unfortunately, it is a bit noisy. I'm thinking of plotting the data in frequency domain , then designing a filter to get rid of the high frequency noise. Unfortunately, it seems that the FFT function requires a uniform sampling rate, but my data comes in at a variable sampling rate, from 10^-5 to 10^-4 sec. Does anyone know of a method of getting basically a power plot so that I can design a low pass filter for the data set? It seems that the fft() function needs a uniform sampling rate. I hope this makes sense. Thank you!