Denmark and Sweden have temporarily reintroduced border checks in an attempt to control the migrant flow, but Jensen said much of the problem stemmed from poor planning in their larger southern neighbor.
"I think that Merkel has been surprised by the number of refugees coming to Germany. She thought this was a crisis that would fade out," Jensen told guests at a US think tank during a visit to Washington.
"She has been accused actually of being the one sending out invitations to refugees around the world, 'Please come to Germany, you are welcome here, we have a house and a job and it's a great place to be'," he said.
Merkel is under intense domestic political pressure to put a cap on refugee arrivals after more than a million -- many fleeing war in Syria and Afghanistan -- arrived in Germany last year alone.
Instead, she has taken the lead in negotiating a deal with Turkey to send back migrants arriving on the shores on Greece in exchange for EU help in dealing with the 2.7 million refugees on Turkish soil.
"So after being too late too little she is now taking on responsibility, and I think she is doing a tremendously good job," Jensen said, complaining that other EU members were being kept in the dark.
"Sometimes she perhaps should remember to inform and listen because even given how strong she can be and how large and strong Germany is, they can't decide for the rest of the 27."
Jensen also met with his US counterpart Secretary of State John Kerry, who assured him that Washington does not regard the refugee crisis as Europe's problem alone.