NFLPA executive director DeMaurice Smith has warned the NFL and the owners of all 32 teams that the players' injury compensation packages must be increased if they were to expand the playoffs.
However, Smith has warned that the players must be consulted first and that there to be agreements in place to ensure their safety in playing the extra games.
"The players have not seen a press release from the NFL indicating that they were going to take up the issue of better workers compensation benefits or increased injury protection benefits in light of their desire for extra playoff games," Smith told USA Today.
"A credible commitment to player health and safety has to include more than a group of Owners voting to recommend playing more games."
The NFL and the NFLPA previously had a dispute over the collective bargaining agreement which saw a lockout take place in the off-season of the 2011 campaign.