Macron's comments appeared to be a defiant reaffirmation of controversial remarks he made last week not ruling out sending Western troops to Ukraine that sent a shockwave around Europe.
"We are surely approaching a moment for Europe in which it will be necessary not to be cowards," he said on a visit to the Czech Republic as the Czech government pushes a plan to buy weapons outside Europe for Ukraine.
"War has returned to our land, powers that refuse to stop are extending the threat each day," he told members of the French community at the start of his one-day trip.
"We will have to live up to history and the bravery it implies," he said.
Most of Macron's European allies said they would not send troops to Ukraine after his comments on February 26, while French officials also insisted any such forces could be sent to back operations such as de-mining rather than fighting Russian forces.
Macron was on Tuesday also due to meet Czech President Petr Pavel and Prime Minister Petr Fiala, and address a nuclear forum.
At a security conference in Munich last month, Pavel said the Czech Republic -- an EU and NATO member of 10.8 million people -- was able to collect a substantial amount of weaponry for Ukraine outside the continent.
He said that, working with Canada and Denmark, the Czechs had "identified" 500,000 rounds of 155-millimetre ammunition and 300,000 122-millimetre shells "which we would be able to deliver within weeks" with the needed funds.
The Financial Times said Prague was looking to amass $1.5 billion to pay for the munitions for Ukraine, which has been battling the Russian invasion for two years.
Fiala said at an international conference in Paris last week that around 15 nations were ready to join the initiative, including France.
Macron said his country would take part in the initiative but did not disclose any details as to how much it would contribute.
The Netherlands, for instance, has already pledged to donate 100 million euros ($108.5 million).
Prague now expects the French leader to come up with a specific pledge during Tuesday's talks.
A French adviser said the Prague visit would be an opportunity to "discuss this initiative" and come up with further specifications.
This would be a bit of a breakthrough as Paris has so far tended to funnel defence spending into its domestic industry and favoured weapons production on European soil for EU money.
Macron also stirred controversy last week when he suggested the West might send soldiers to Ukraine, an idea largely rejected by France's allies.
The French government later said the suggestion did not concern combat troops.
Later on Tuesday, Macron is due to address a nuclear forum in the Czech capital, attended by several French energy companies.
These include the power giant EDF, nuclear fuel distributor Orano and nuclear reactor producer Framatome.
EDF is one of two bidders in a multi-billion Czech tender to build up to four new units at its two nuclear power stations, alongside South Korea's KHNP.
Macron's visit to Prague follows an invitation from Pavel during the Czech president's visit to Paris last December.
That visit was shadowed by a deadly shooting in Prague, in which a student killed 14 people and then himself at Charles University.
Macron, who was quick to offer condolences to his guest Pavel, will lay flowers at the site on Tuesday.
