The smoking woman is a lady who put out her cigarette on a tree in "The One With The Cop". She is played by NiCole Robinson.
When Phoebe sees her put out her cigarette out on tree, she acts as a cop who will arrest her if she does not apologize to the tree. At first, the woman takes it as a joke, but Phoebe pretends to call for back up which leads the lady to apologizing to the tree.