Both the government and Emergency Medical Care Inc. expressed their disappointment at the union's rejection of the proposed contract, which included a defined benefit pension plan.
"It's the second rejected tentative agreement that their union ... recommended that members should ratify," Stacey Brown of Emergency Medical Care Inc. said in an email.
She said the company wants to meet with the union to discuss what happens next.
Local 727 of the International Union of Operating Engineers has agreed there won't be a legal strike before July 5, Brown said.
The union could not be reached for comment and did not release vote results. The company and the provincial government confirmed the deal had been rejected.
The defined benefit pension plan appeared to be a major sticking point during negotiations. A defined benefit plan requires an employer to meet set retirement payments based on a formula that factors in an employee's years of service and earnings, as opposed to a less lucrative defined contribution plan.
The tentative agreement was reached June 9 with the help of a mediator, two days before a legal strike deadline that was set by the union.
In an email, Labour Department spokeswoman Chrissy Matheson said the government believes the rejected deal was reasonable.
"We are encouraging the employer and the employee to get back to the table as soon as possible," said Matheson.
Earlier Thursday, Premier Darrell Dexter refused to speculate about the union vote and he refused to comment on reports that allege the government was directly involved in previous negotiations to ensure the defined benefit pension provision was part of the deal.
"I'm not going to get into the way collective bargaining takes place," said Dexter. "That's an internal matter."
Dexter has previously said Emergency Medical Care Inc. was told money would be made available to pay for the pension plan.
Health Minister David Wilson also wouldn't comment on whether he discussed negotiations with union members, saying only the government would have more to say once the vote results were known.
Progressive Conservative Leader Jaimie Baillie called on the government to clarify its role in the contract talks after the deal was rejected.
"I think the government has to come clean about what promises where made behind the scenes that we don't know about, that led us to this result today," said Baillie.
Baillie said he believes collective bargaining could still produce an agreement if there is no outside interference.
He wouldn't say whether anti-strike legislation should come next, but he didn't rule it out either.
"I think every step that prevents a breakdown in emergency services needs to be considered," Baillie said.
The province's paramedics aren't covered by essential services legislation that requires some staff to remain on duty in the event of a strike.