Statements made by Defence Minister Claus Hjort Frederiksen suggest that Denmark may be required to accept the return of citizens who have fought for the group, reports broadcaster DR.
Several hundred Isis fighters are currently imprisoned in Syria, where the movement has gradually been subdued in recent years. A number of the captured individuals are Danes.
"We are working on finding out how many there are. We must then take a look at their cases," Frederiksen told DR Nyheder.
The minister's statements come after a meeting between countries taking part in a military coalition against Isis, including Denmark. The United Stated reportedly made it clear it would prefer home countries of the militants to take them back.
Around 150 Danish citizens have joined militant religious movements in Syria and Iraq since 2012, according to DR's report.
Frederiksen told the broadcaster he would prefer them to go on trial in the countries where their crimes were committed.
"They have beheaded people, raped women and children and sold people. For me, it is paradoxical for those militants to now claim Western norms regarding protection of rights," he said.
"I think it's pathetic for those people to ask to be given the safety in Western countries that they so despicably wanted to defeat," he added.
But the minister added that the Syrian coalition partners the Syrian Democratic Forces, an alliance of predominantly Kurdish forces, should not be left with sole responsibility for dealing with the issue.
"We must not let down an ally by trying to leave everything at their door. We must therefore look at cases specifically," he said.