"This is a grave situation".
Lim (62) was imprisoned in North Korea in 2015.
Freeland's remarks came as Trump delivered another warning to Pyongyang that the USA military is "locked and loaded" if the regime acts unwisely.
Family spokeswoman Lisa Pak said in a statement Thursday that "there is a long way to go" in terms of Lim's healing and said he needs privacy while receiving unspecified medical attention.
"What North Korea is doing is absolutely unacceptable, and it's posing an unacceptable security threat both in the region and to the entire world", she said.
Asked about Trump's language on North Korea, Freeland said Canada stands by all of its allies, including the United States.
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Freeland said Canada is "working with our worldwide partners to seek a resolution, a de-escalation" in the situation.
"It is of absolutely pressing concern for Canada and we are very involved working with our global partners to seek a resolution, a de-escalation, to really get North Korea to understand it must get off of this path which is so destructive for North Korea and the world".
A Canadian pastor who was released from imprisonment by North Korea three days ago, returned home on Saturday.
The pastor's son James Lim said his dad was happy to be back home in Canada, stopping for coffee and a donut at Canada's popular Tim Horton's coffee chain on his way home from the airport. "When they are threatened, we are there", she said. "That is a very separate and distinct issue".
Lim, a leader of one of Canada's largest churches, had been sentenced to hard labor for life in December 2015 on charges of attempting to overthrow the North Korean regime.