Risk of Italian strike increases
The Italian Players Union (AIC) has already emphasised it will not play at the weekend if the League does not sign the agreement, which has been the subject of negotiations for the last year.
"The League's general assembly has rejected the agreement with the players by a large majority, 18 votes against two," League president Maurizio Beretta told reporters.
A meeting of the Italian FA, due to be held on Wednesday evening, was postponed until the following morning.
AIC president Damiano Tommasi reiterated his members would only play if the agreement was signed.
"At the moment, we aren't in a position to play," he told reporters. "The League's demands are spurious and I don't see that this is going to change."
Strike action was twice narrowly averted last season as AIC and the League tried to thrash out a new collective agreement to replace the previous one which expired at the end of the 2009/10 season.
The main sticking point concerns players who are no longer wanted by their clubs.
The AIC wants guarantees that these players will not be forced to train separately from their squads or be forced to move. The clubs want their coaching staff to be allowed to make the decision.
The League said in a statement it also wanted to insert a clause confirming the players would pay a new solidarity tax announced by the Italian government this month on all workers earning over 90,000 euros a month.
"The text cannot be signed without inserting a clause placing the payment of the extraordinary contribution exclusively with the players and another allowing the autonomy of the coaching staff in the organisation of the squad," it said.
The AIC says it has been waiting since last year for the League to sign the agreement.
The start of the Spanish league season has been postponed this month because of a dispute between the players' union there and the football league.