You can always ask.
Asking will sometimes open up the owner or the agent to letting you know more than they normally would.
If they wil not negotiate, they may not want you as a tenant, or they may just not be in the habit of doing that.
(Please note: when you choose an answer as a Best Answer, or at least give a thumbs up, it helps those who answer questions here.)
Dear Paola, the price is very rarely negotiable. There is no need for the LL to compromise. The inventory is low, so the answer on your lower offer will be NO. Guaranteed. Unless there is a reason to negotiate. Please call me for a specific question and I'll get you an answer. There are too many people who want to live in Cambridge and not enough inventory. Lilia, 617-901-7413.