Western forces on Friday agreed increases to their military support for Ukraine, but Germany wavered on further EU tank deliveries despite mounting calls from Kyiv and fellow allies.
He stressed that he intends for Berlin to be prepared if and when a decision is taken on Leopard 2 tanks.
Ukraine has repeatedly asked for battle tanks from its Western allies, with Germany's Leopard 2 units being of particular interest.
Ukrainian President Volodymyr Zelenskyy has insisted that receiving supplies of Western tanks must outpace another Russian attack.
In the hours before the meeting, the Kremlin said that Western tanks for Ukraine would "change nothing" and would not stop Russia from achieving its goals, Reuters reported.