He called it an “invitation,” but warned that anyone who did not comply would face consequences.
However, a spokesman later denied the possibility of a call-up.
On Tuesday, President Zelensky told journalists that 450,000-500,000 new soldiers were needed, but that doing so would be a “sensitive issue.”
This comes as Ukraine’s recent counter-offensive appears to be coming to a halt.
There have also been setbacks in aid provisions for Kyiv, with US Republicans blocking a $61 billion (€55 billion; £48 billion) military package and Hungary blocking an EU financial deal worth €50 billion ($55 billion; £43 billion).
In a November analysis of Eurostat data, BBC Ukrainian discovered that 768,000 Ukrainian men aged 18 to 64 had left the country for the EU alone since Russia’s full-scale invasion began.
The figure excludes citizens living outside the EU or those who have lived abroad since before February 2022.
Mr Umerov described the recruitment drive as “not a punishment” but “an honor” in an interview with Die Welt, Bild, and Politico.
“We are still discussing what should happen if they don’t come voluntarily,” he went on to say.
However, a ministry spokesman later appeared to deny any kind of coercion was involved.
“There is no discussion on the agenda of a call-up from abroad,” Ukrainian media quoted Illarion Pavlyuk as saying.
“If citizens of Ukraine want to join [the army], they come to Ukraine to join.”
There are no recruitment centers outside of Ukraine, and the Ukrainian government has no way of forcing anyone to attend them.
According to the defense minister, it is critical to be fair in informing mobilized men about how they will be trained and equipped, when and where they will serve, and when they will be discharged.
In his end-of-year news conference on Tuesday, Mr Zelensky suggested that there were currently 500,000 Ukrainian troops at the front.
He also stated that there were problems with rotation and holidays. Conscripts and volunteers are currently required to serve until the end of the war and are only allowed 10 days of leave per year.
In comparison, Russian President Vladimir Putin stated this week that 617,000 Russian troops are participating in the so-called “special military operation” in Ukraine.
The BBC is unable to independently confirm troop counts.