Please please negotiate! Assuming you are a woman, all the research shows far greater proportion of men automatically negotiate every salary offer/ promotion/ step, while very few women do. It is one of the factors that leads to a pay gap! (Not denying all the other discriminatory factors of course!)
That doesn't mean you need to burn your bridges or get all fierce of course. And if you are nervous you can do it by email... some basic suggested phrases you might want to use:
"Thank you for your offer. Based on my experience level and the responsibility level of the position, I was expecting higher. What flexibility do you have?" Or
"I'm wondering what your range is, because I would be happier with a bit more" or, "How much could you increase that by, and still go home happy?" (This normally draws a smile and is a good way to make it feel collaborative.
If you are doing it in person, then Don't spend ages justifying or fill the awkward silence. Doing that helps them mentally prepare their own justification / make it easier for them to say no. Just ask the question then give the silence. Pressure is on them.
If they do say no, then ask "where do you have flexibility?"
Pause again. This might bring offers around other terms...
If they say they don't, then accept graciously, say "well I understand for now you seem to be working within strict constraints, and I'm passionate about the role and excited about joining, so I accept your proposal. I would like to ask, though, for a review after six months."
Something like that might get you something, but is unlikely to piss anyone off! More likely to build your status if anything as a straight talker with healthy assertiveness.
Good luck!