You cannot be fired for serving
The Discharged Soldiers (Return to Work) Law of 1949 (חוק חיילים משוחררים (החזרה לעבודה), תש"ט-1949) bars an employer from dismissing an employee because of reserve service. An employer who wants to dismiss a reservist during or around their service must go through an employment committee (va'adat ta'asuka) and obtain a permit; they cannot simply fire you.
A 2024 amendment, passed as reserve call-ups lengthened, extended the protected period: reservists who served long stretches (60 or more days in the relevant war-period window) gained a longer post-service window during which dismissal is restricted. If you were dismissed close to a long reserve stint, this protection may apply to you.
The self-employed angle
The job-protection law is written for employees, so the self-employed do not get "no-firing" protection. Their protection is financial: the chapter 3 Tax Authority grant exists precisely because a self-employed reservist has no employer to keep their income flowing. If you are self-employed, your "job protection" is making sure you actually claim that grant.
For employees navigating a dismissal or a dispute tied to reserve service, the israeli-bituach-leumi skill points to the relevant rights and the bodies that enforce them.