Krzysztof Szczerski made the statement at a session of the UN Security Council on Ukraine on Tuesday night, Polish state news agency PAP reported.
He said that accepting Russian conditions would only embolden Moscow to take further aggressive action.
Meanwhile, the United States has urged both Russia and Ukraine to make tough concessions.
Tuesday's session of the UN Security Council had been called by Slovenia, which presides over the body in December.
Szczerski said Poland was pleased that peace talks had started and echoed US President Donald Trump's call for immediate ceasefire, but added that Poland's reservations about Russia's readiness for peace "have unfortunately turned out to be right."
Poland's UN envoy said that Moscow was sticking to its "maximalist aims," according to which Ukraine is being portrayed as "devoid of sovereignty, territorial integrity and effectively freedom."
He warned that "acceptance of this would represent a dangerous step back for global principles which give us security."
Szczerski said: "If we want lasting peace, we cannot accept Russian conditions."
He added that "this would only embolden Russia to continue its aggressive policy."
"Peace must be based on the fact that Ukraine is the victim, and Russia the aggressor," Szczerski also said.
He told the gathering that Ukraine was expressing "readiness for peace," unlike Russia and its President Vladimir Putin, who he said was escalating attacks and threatening to "extend the war to Europe."
Szczerski emphasised that the international community must not forget about Russian crimes.
In this context, he mentioned reports that abducted Ukrainian children were being sent to camps in North Korea.
"Peace will only be real if it’s based on international law," Szczerski said. "Any deal that rewards Russia’s aggression would only lead to more war."
During Tuesday's debate, Russian representative Vassily Nebenzia said Russia "isn't a threat to anyone." He accused European countries of aiming to prolong the war in Ukraine "to buy time to prepare for war against Russia."
Meanwhile, the US representative called on both sides to make "painful choices" and to "embrace peace."
Ukrainian envoy Andriy Melnyk compared "the futile debates" at the UN Security Council to Samuel Beckett's play Waiting for Godot.
"Beckett teaches us that inaction means complicity," he said.
Melnyk also called on the countries that buy Russian raw materials, especially China, India and Turkey, to stop such purchases.
The Ukrainian envoy accused these countries of hypocrisy and of allowing Russia to continue its aggression, the PAP news agency reported.
(pm/gs)
Source PAP