Germany has not yet decided whether to send the tanks to Ukraine, or allow other countries to donate theirs, despite pressure on Berlin to act.
"We had a frank discussion on Leopards 2. To be continued," Oleksii Reznikov said after meeting Western allies.
Kyiv is to get many other Nato weapons.
The meeting at Ramstein Air Base in Germany did bring an agreement to supply more armoured vehicles, air defence systems and ammunition.
But the Leopard 2 is seen as a potential game-changer for Ukraine, as it is easy to maintain and designed specifically to compete with the Russian T-90 tanks, which are being used in the invasion.German Defence Minister Boris Pistorius said opinions remained divided over supplying Leopards, and he denied that Berlin was blocking such a move.
Under German export laws, other countries who want to supply Leopards - like Poland and Finland - are unable to do so until Berlin gives the all-clear.
Ukrainian President Volodymyr Zelensky praised the Nato partners for their military assistance, but said "we will still have to fight for the supply of modern tanks".
"Every day we make it more obvious that there is no alternative, that a decision about tanks must be made."
Ukraine's current tanks are mostly old Soviet models, often outnumbered and outgunned by Russian firepower.
More than 2,000 Leopards are sitting in warehouses all over Europe. President Zelensky believes about 300 of them could help to defeat Russia.
Mr Pistorius said Berlin was prepared to move quickly if there was consensus among allies, though he could not say when a decision on the tanks might be made.
Germany has found itself in this standoff due to several factors including international diplomacy and the legacy of World War Two.
It used to have a policy of not sending arms to conflict zones, but that was reversed last February after Russia's invasion.
Late last year, Nato chief Jens Stoltenberg said Germany was now "among the allies providing most military, financial and humanitarian aid to Ukraine", by supplying artillery, air defence systems and Marder infantry fighting vehicles.
But Germany is reluctant to send Leopards unless they are part of a wider Nato package that preferably includes America's powerful M1 Abrams tanks. The US has rejected this, saying the Abrams tanks are impractical for Ukraine's forces because they are difficult and expensive to maintain.
Regardless, there has been pressure in some corners for the US to send its tanks, to get Germany to do the same.
US Defence Secretary Lloyd Austin denied Berlin was waiting on the US to make the first move. "This notion of unlocking - in my mind it's not an issue," he said after Friday's meeting of 54 countries at Ramstein Air Base.
Germany also remains haunted by the Nazi-era devastation it caused in World War Two, and Chancellor Olaf Scholz is believed to be cautious about having anything to do with an escalation in Ukraine.
A leading opposition Christian Democrat (CDU) politician in Germany, Johann Wadephul, condemned the government's "policy of refusal" on the Leopards, saying it would affect Germany's international reputation. "What is Scholz waiting for?" he asked.
Poland's Foreign Minister Zbigniew Rau also criticised Germany's reluctance.
"Arming Ukraine in order to repel the Russian aggression is not some kind of decision-making exercise. Ukrainian blood is shed for real. This is the price of hesitation over Leopard deliveries. We need action, now," he tweeted.
Western countries have committed billions in other weaponry - but without Germany's commitment on tanks, it was not the result Ukraine was hoping for.
Other countries have committed to sending tanks, including the UK, which will send 14 Challenger 2s.
The US announced fresh support worth more than $2.5bn (£2bn) this week, including armoured vehicles.
The Pentagon promised an extra 59 Bradley armoured vehicles, 90 Stryker personnel carriers and Avenger air defence systems, among other supplies.
Nine European nations have also promised more support of their own after meeting on Thursday in Estonia. They included: