Hey, Cleo. Don't go scampering around too much, okay? You only just joined the kindergarten.
Literal
Oi, Cleo. Too-much scamper-about don't-do-[ね]? Still enroll-did just-ばっかり is-[explanation-なんだぞ].
Likely addressed to a child or a small pet. うろちょろ is a mimetic adverb for restless, small-scale scampering about — the kind a child or small dog does. するなー is the plain prohibitive imperative する+な (don't do), stretched into a softer な-ー ending. 入園したばっかり ('just enrolled') uses ばっかり (contraction of ばかり) meaning 'just / only recently.' 入園 specifically means 'enter a kindergarten or preschool.' なんだぞ gives masculine-emphatic explanatory force.