Hi, and thank you for your question.
The agencies themselves don't list minimum loan amounts, but individual lenders may impose minimums. That's because regardless of loan size, every mortgage requires a lot of work on the part of a lender -- processing, underwriting, auditing, document generation, and conforming to government guidelines at every step. That's expensive, and a small loan may actually cost the lender money. Most of us don't want to pay for the privilege of doing our work, and neither do mortgage lenders. Some will make smaller loans but add a low loan amount surcharge.
You may have to work a little harder to find a lender for a smaller loan, but financing should be available. Good luck.