This place is ok if you happen to be staying in Bocagrande, but I don't think it merits a taxi ride to it if you are staying in the Old Town.
It has the usual Arabic fare of tabulleh, hummus, fatush, falafel etc, but not a lot else if you are vegan.
And at ~USD 20 for a full plate of the stuff, it's not cheap either. Shame their stuffed vine leaves and stuffed cabbage leaves are both premade and meat infused. :(
BTW: Note this place has changed its name to: Restaurante Arabe
Cons: Limited choices, Bit pricey