His comments were in response to Mr Zelenskyy accusing his US counterpart of living in a "disinformation bubble" after Mr Trump blamed Ukraine for the war.
When asked if Mr Trump blames Russia or Ukraine for the war - which was launched by Moscow in February 2022 - Mr Waltz would not give a direct answer.
In recent days Mr Trump has wrongly claimed Mr Zelenskyy has an approval rating of just 4% in Ukraine - despite recent polling which showed it is at 57%.
He went on to insist Mr Trump is the best person to negotiate with Russia's Vladimir Putin, despite concerns the US will force Ukraine into concessions after kicking off talks this week without Europe or Kyiv.
French President Emmanuel Macron, who is due to meet with Mr Trump in Washington on Monday, said he would tellthe president not to be "weak" on Mr Putin.
