What is this rose pest
Thank you for attaching the excellent image of these very small pests. They are aphids, not the much smaller thrips. Fortunately, aphids are among the easiest garden pests to manage.
Two very effective, also non-toxic, tactics are to squish them as soon as you see them; or to wash them off with a harsh water spray. Repeat as needed every several days.
Gently washing off your rose every several days will reduce honeydew, the sticky excretion from the aphids which attracts ants. (A droplet is on the stem, toward the upper left.) Wash them early in the day so that the leaves dry within several hours, thereby also limiting leaf problems common to roses.
Also see “Controlling Diseases and Aphids on Your Roses” (https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1520_0.pdf)
Enjoy your garden!