I recently came upon several lines of poetry attributed to Prudentius Silentarius which are very close to the lines in Donne's Elegy 19 beginning "Full nakedness! All joys are due to thee!"
I still have to find source of the Prudentius passage; but in looking at the editions of Donne's poetry available to me (and someone else checked the Variorum for me, also--I don't have access to it), there's no mention of Donne's lines having a source or analogue.
these lines are possibly what you are looking for. They are by Paulus Silentiarus and indeed come from the Greek Anthology (the Loeb edition, translated by W.R. Paton):
BOOK V. 252.— PAULUS SILENTIARIUS
let us throw off these cloaks, my pretty one, and lie naked, knotted in each other's embrace. Let nothing be between us; even that thin tissue you wear seems thick to me as the wall of Babylon. Let our breasts and our lips be linked ; the rest must be veiled in silence. I hate a babbling tongue.