The prime minister - who has been a strong advocate for providing Ukraine military support - told reporters on his way to meet Mr Macron in Paris that the war "will end as all conflicts do, at negotiating table".
Both leaders are meeting at the Élysée Palace to, among other things, discuss their response to Russia, with Mr Sunak saying ahead of the trip "new and unprecedented threats" mean it is "vital that we fortify the structures of our alliance".
The pair agree the conflict must end with talks but both want Ukraine to gain the advantage in the war in order to get Vladimir Putin around the negotiating table.
Speaking on the Eurostar, Mr Sunak said there's consensus in the West that "now is not the time for negotiations, and I think everyone at the moment is united, as I was saying, in providing Ukraine with the additional support that they need in order to have a decisive battlefield advantage."
He added: "Of course, this will end as all conflicts do at negotiating table, but that is a decision for Ukraine to make.
"And what we need to do is put them in the best possible place to have those talks at an appropriate moment that makes sense for them.
"But at the moment, the priority is got to be giving them the resources the training and the support they need to push forward and create advantage on the battlefield."
He was responding to questions about comments Mr Macron had made recently, saying Ukraine should not seek to "crush" Russia.
"I do not think, as some people do, that we must aim for a total defeat of Russia, attacking Russia on its own soil," Mr Macron told the paper Le Journal du Dimanche.
"Those observers want to, above all else, crush Russia. That has never been the position of France and it will never be our position."
He told a Munich press conference in February the only way to "bring Russia back to the table and build a lasting peace" would be to support Ukraine's war effort.
It is not clear how President Volodymyr Zelenskyy will react to Mr Sunak's comments, but it appears he did not take kindly to Mr Macron's.
Rebuking the remarks, he told Italian newspaper Corriere della Sera it would be "a useless dialogue".
"In fact Macron is wasting his time. I have come to the conclusion that we are not able to change the Russian attitude."
He added: "If they have decided to isolate themselves in the dream of rebuilding the old Soviet empire, we cannot do anything about it. It is up to them to choose or not to cooperate with the community of nations on the basis of mutual respect."
It follows an intervention from one of Russia's few world allies, China, which recently urged the warring nations to announce a cease fire and hold talks.
Beijing released a 12-point paper revealing its position on the conflict in late February, saying all countries’ “sovereignty, independence and territorial integrity” be guaranteed.
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“Dialogue and negotiation are the only viable way out to resolve the Ukraine crisis,” the paper added.
Mr Sunak, asked if he was concerned China could be stepping up its cooperation with Russia, said it was "definitely something that I'm planning to spend some time talking to Emmanuel about later".
"We'd urge all countries not to be providing support to Russia, or trying to circumvent sanctions," he said.
"So that is something that we'll be talking to him about later on is just a joint approach, not just to China, but there are other global challenges that we face, whether that's Iran or or others, and we just want to make sure that as countries that as I said, we're not just neighbours, partners, friends, you know, our values are aligned.
"We should be standing together to defend the things that we care about.”