Asked whether he agreed with the motion that Zionism is racism, Polanski, who is Jewish, said: "I grew up in a Zionist household and I grew up with the idea that that region was a land without a people and a people without a land and as I've educated myself, learned, discovered, I don't believe that's true.
"And what we're seeing is an ongoing genocide and the displacement of the Palestinian people. I believe that's clearly racist."
Israel has repeatedly denied its actions in Gaza amount to genocide.
The International Court of Justice (ICJ) is currently hearing a case brought by South Africa that accuses Israeli forces of genocide, but it could take years to reach a conclusion. Israel has called the case "wholly unfounded" and based on "biased and false claims".
Pressed again over whether he agreed that "Zionism is racism", Polanski said: "The displacement of the Palestinian people, the genocide, is totally racist."
Asked if he would apologise to Jewish people upset by the vote on the motion, Polanski said: "It's my job to reassure people and to make sure that we bring our party together.
"Nobody will be excluded in the Green Party based on faith and religion."
He denied he had lost control of his party, adding: "I've got a party that was 55,000, 60,000 members when I was running for leader, [which] is now 220,000.
"Any member is entitled to their opinion for a democratic grassroots party."
Those who were supportive of the motion want Polanski to come out and explicitly declare it was now party policy.
However, those against it want him to distance himself from the motion and make it clear that he does not support it.
Lucas's comments came shortly after polls closed in the Holborn and St Pancras by-election, but before the result was declared.
Lucas, who voted against the motion, said: "I would have hoped [Polanski] would have been a very strong critic of this motion."
She added that it was "flawed from top to bottom".
Asked if Polanski should stand down, she told the BBC's Newsnight: "I think let's just see what happens in the coming days and weeks. Obviously he has been completely taken up with this by-election.
"I want him to speak now about what's happened, I want him to show the leadership that was frankly missing on Sunday.
"I think the jury is out about whether he will do that - but I very much hope he will."
The motion overshadowed the final days of Polanski's by-election campaign, where the Greens had been hoping to overturn a substantial Labour majority in the seat vacated by former Prime Minister Sir Keir Starmer.
Although Polanski lost out to Labour's Sagal Abdi-Wali, the party saw its majority reduced from 11,572 to 3,364.
The motion has sparked days of controversy and exposed divisions between the Green Party's newly enlarged membership base under Polanski and its MPs elected at the last general election.
Four of the five Green MPs opposed the motion, while the party's co-deputy leaders were split over whether they supported it.
The vote also led to the resignation of the Green deputy leader in Wales and condemnation from the European Green Party, as well as the Jewish Leadership Council and the Board of Deputies of British Jews.