We broke the story ... DaBaby's security's accused of violently punching a man's face and head outside the Centro Night Club in Lawrence, MA last Friday night after the fan allegedly got aggressive when he was declined a photo with the rapper.

Interesting thing is, the guy who got pummeled is a fellow rapper named Don Trag ... who opened for DaBaby at the concert. DaBaby never took the stage -- he bounced after his crew's altercation with Trag. But, NTS Entertainment says he took the $22k he was paid for the show anyway.

NTS tells TMZ that's all fine and good ... as long as he reschedules and comes back to do a show at a later date. The company says it's in the early stages of negotiating with DaBaby, but would be willing to book the gig at a different venue in Boston or Connecticut.

We're told NTS expects to work it out with the rapper and hopes to avoid getting lawyers involved ... but we've learned Traq has already lawyered up and he's going after DaBaby for the vicious attack.

Sources close to DaBaby tell us his contract specifically states ... if his safety becomes a concern he has every right to leave. We're told his side feels the venue failed to provide adequate security to keep overzealous fans like Trag at bay ... which is why his crew had to handle it.

NTS confirms the contract mentions DaBaby could leave if he felt security was inadequate ... but not that he could take the money and run without performing. It also denies there was any security risk.

If both sides fail to come to an agreement, NTS tells us it would have no choice but to take legal action for breach of contract, but it really just wants DaBaby to do the show down the road.

As for the beatdown outside the club ... Trag's family says he's still dealing with his injuries. His mother originally told us he was in a coma and in seriously bad shape ... and they've been in touch with lawyers about the incident.