Dennis Rodman just sent a message to Donald Trump -- call me, so we can make peace with North Korea together! 

And yeah, he's dead serious. 

The Worm -- who just got back from N. Korea -- sat down with Michael Strahan on 'GMA' and laid out why he thinks he and Trump can make real progress with Kim Jong-un

Strahan pushed Rodman about the fact Jong-un's a dictator and the mysterious death of ex-NK prisoner Otto Warmbier ... but Dennis continued to insist the North Koreans are good people who are just misunderstood.

While Rodman wouldn't personally take credit for Warmbier's release -- his agent sure did ... insisting Dennis' trip was a key factor in Jong-un's decision to free the 22-year-old American. 

Rodman's agent says he specifically asked about Warmier's release 3 times before this most recent trip -- and says, "I know being there had something to do with it."

Warmbier's family says BS -- insisting the NBA legend had nothing to do with it.