Eleven security forces troops were killed on December 18th and 20th in Karak, Jordan. In addition, a Canadian tourist and two civilians were also killed along with five gunmen. The Islamic State jihadists claimed responsibility for the initial attack.
The statement by the ministry was published in Jordanian media but it didn't go into details as to why the imams refused to comply with a nationwide call to hold memorial prayers following the attacks, but it would be a good guess to say that the imams in question are sympathetic to the more orthodoxy of the Islamic State.
There should be no doubt that many imams, not only in Jordan, but throughout the Muslim world, are sympathetic to IS and their fundamentalist ideological view of Islam.