Maybe - but I don't think so. I don't know of its core's neutronics, but I would think even the minimum flux for criticality would produce interesting anomalies that would make it impractical. However low power and short operation would immediately send up the red flags on the plant.
I'm sure that we've got good folks who have modeled the plant and know the answer. My guess is that the plant can't, but I don't know for sure.
It looks like (see Table II.1) the ~1% of Pu content in a spent fuel rod from a commercially-run, normal-burn-up PWR is ~56% Pu-239, the rest being other isotopes of Pu. 93% Pu-239 would be weapons-grade Plutonium.
I can't find figures for the Pu isotope profile from a PWR deliberately run at low burnup. Likely this is classified information.
The mechanism for achieving low-flux in a PWR seems to be straightforward. On paper at least the Iranians can lower the moderator pressure in the PWR to about 10% nominal to "harden" the neutron flux, effectively reducing the flux of capturable neutrons.
I don't know if the analogy is a good one, but it seems that a 'slow-cooked' fuel rod ends up with higher Pu-239.
Of course, even if it's all as simple as I am naively making out, the Iranians would also need a reprocessing plant to extract the Plutonium. One more thing for the IAF to bomb.