Yes — public buses run regularly along the Adriatic Highway connecting the main coastal towns: Herceg Novi, Kotor, Tivat, Budva, Petrovac, Bar, Sutomore, and Ulcinj. Fares are low and services run throughout the day, making it easy to day-trip between towns without a car.
For beaches that sit right on the highway or just off it — Jaz, Becici, Kamenovo, Sutomore, Crvena Plaza near Bar — the bus drops you close enough to walk. Mogren and Slovenska Plaza in Budva are walkable from the bus station in the old town.
More remote stretches like Buljarica or the Lustica Peninsula are less well served; for those you'll need a taxi, boat, or car. Ask locally, as schedules change seasonally and smaller operators sometimes add routes in peak summer.