The National Lacrosse League has rejected the latest proposal for a collective bargaining agreement with the Professional Lacrosse Players Association and announced Thursday that it has canceled the first two weekends of the 2018-19 season.

If the NLL stands by its decision, it will mark the first time in the league’s 30-plus years that a labor dispute has resulted in the cancellation of games. During a similar impasse in October 2007, the NLL announced that it had canceled the 2008 season, only to come to terms with the PLPA nine days later.

The 2018-19 season had been scheduled to begin Dec. 1 with three games: Saskatchewan at Georgia, Toronto at Buffalo and Calgary at Colorado. Week 2 was to feature New England at Rochester, Colorado at Saskatchewan, Toronto at Vancouver and Buffalo at San Diego — the debut for the expansion Seals — on Dec. 8.

As of Thursday, those games are now off the table. The NLL, whose last offer was presented Oct. 31, originally gave the PLPA a deadline of 5 p.m. Eastern on Wednesday to counter after reportedly rejecting a one-year PLPA proposal that would act as a stopgap to save the start of the season while negotiations continued. The league suspended the deadline to allow the PLPA additional time to finalize its latest counterproposal.

“It is clear we cannot accept the terms the PLPA has put forward, and therefore, have made a decision to reject it,” the NLL said in a statement issued to media Thursday. “We believe those terms would have both short- and long-term negative consequences on our member clubs and the league which we are not willing to accept.”

With the PLPA instructing players not to attend training camps or submit to physicals in the absence of a collective bargaining agreement, the NLL contends it had no choice but to cancel the first two weekends of the season.

The NLL detailed its stance in an additional and lengthier statement published on the league’s official website.

“A guaranteed 400[-percent] increase in expenses without a corresponding guaranteed revenue increase is not something as stewards of the league we can responsibly agree to,” the statement said. “We have put a very good and fair offer on the table, which includes a 25[-percent] increase in salary and benefits for the players. It is a significant improvement from where the players were at the beginning of their last employment agreement and a testament to our ownership’s commitment to continue to invest heavily in our sport and grow the league.”

The players opted out of the last collective bargaining agreement in November 2017. PLPA president Peter Schmitz has said the NLL’s offer to share ticket-based revenue with the players falls short of their demands for an equitable portion of sponsorship, concessions, parking and merchandise.

The NLL said its offer provides “a fair calculation of bonuses to be paid to the players” that factors attendance growth and percentage increases “to account for growth in all attendance-related revenue streams.” The league also noted that the players already receive a share of sponsorship, TV and expansion fees.

The labor impasse has stalled momentum for the professional indoor league, which is set to unveil new franchises in San Diego and Philadelphia this year, with the Rochester Knighthawks relocating to Halifax next year and two new expansion teams expected in Rochester and Long Island. Boston and California’s Bay Area also have been linked to expansion talks.

“For the good of everyone including players, owners and our fans, we are attempting to run the league as a business so that its long-term health and success is assured,” the NLL said on its website. “We have seen steady, but only incremental success. This nascent growth will only continue if ownership, management and players all work together to achieve it.”

Reporting by Jack Goods and Marisa Ingemi contributed to this article.