Trump's campaign called Aurora a "war zone" in a Tuesday statement announcing Friday's rally ... claiming an influx of migrants is bringing chaos and fear to the city, with a Venezuelan gang terrorizing apartment complexes and forcing locals to flee their homes.

The campaign announcement makes it sound like Trump's going to keep fanning the flames and paint Aurora as a once-promising city besieged by dangerous migrants ... but the town's top elected official says, not so fast.

Mike Coffman, Aurora's Republican Mayor, said in a statement ... "The reality is that the concerns about Venezuelan gang activity have been grossly exaggerated."

Viral videos from back in August showing armed gang members allegedly taking over entire apartment complexes in Aurora -- part of the Denver metro area -- became a big talking point during the Trump campaign ... but Coffman says the situation is not as dire as Trump makes it seem.

Coffman says, "The incidents were limited to several apartment complexes in this city of more than 400,000 residents."

Despite the fact check, Coffman is welcoming Trump with open arms, and Coffman wants to use the visit as "an opportunity to show him and the nation that Aurora is a considerably safe city -- not a city overrun by Venezuelan gangs."

A source tells TMZ ... Coffman's office has NOT had contact with Trump's camp yet, but the Mayor's offer to show Trump around town and give DT a police briefing still stands. For the moment ... the only coordinating has been for security.

Mayor Coffman has no plans to attend the rally, we're told.