The Intel MKL libraries are named a bit differently than the generic libraries. You can verify this by looking in your MKL library directory. I've not compiled LAMMPS (I really should, though, it's close to the sort of research that I do), but most packages allow you to set an environment variable like LIBBLAS or something similar to tell the compiler what libraries it's supposed to link against. You might look at http://www.advancedclustering.com/co...-vs-intel.html
-- which suggests that LAMMPS cannot link against MKL directly, but needs to link against its fast fourier transform library (FFTW). For starters, you might try to start with an un-optimizes BLAS/LAPACK just to see if oyu can get the software going. You can install libblas and libblas-devel plus lapack through RHEL's package manager (yum IIRC). Then you can at least get something going while you work on usingthe optimized libraries. You will probably need to consult a resource specific to LAMMPS for exact documentation on how to get it to work with MKL. Good luck!