European leaders are expected to sign off on the treaty at a summit on 30 January to enforce stricter budget controls mainly in the debt-stricken eurozone, but Prime Minister Donald Tusk said Warsaw was seeking concessions.
"If Poland does not win an appropriate status of participant in the eurozone meetings, which would give us a feeling that we take part in the decision-making process ... we will find it difficult to sign the fiscal pact," Tusk said.
"We will not accept such a model."
Tusk may be facing an uphill battle as France strongly opposes allowing non-euro states to attend the single currency area meetings.
Britain has already said it will not join the new intergovernmental agreement, which is open to non-euro countries belonging to the EU.
Poland wants to join the new club partly to showcase its relative economic success and stability amid market turbulence. It is the only EU member to have avoided recession since the global economic crisis erupted in 2008.
Tusk's centre-right government says keeping non-euro outside the currency bloc's core discussions risks splitting the whole 27-nation EU into a two-speed vehicle.