He has called for both sides of the US abortion debate to “tone down the rhetoric”, following an attack on a clinic.
Republican presidential candidate Ben Carson also urged advocates to express their differences in a peaceful manner.
Planned Parenthood has drawn anti-abortion protests in the past.
The clinic provides a range of health services including abortion.
The shooting suspect, Robert Lewis Dear, reportedly said “no more baby parts” during his arrest, sparking speculations that he was motivated by opposition to abortion.
Mr Hickenlooper, a Democrat, told CNN the shooting and similar violent incidences might be a result of the “inflammatory rhetoric we see on all levels”, referring to the heated debate over abortion.
He described the rampage as “a form of terrorism.”
His sentiments were echoed by Republican presidential candidate Ben Carson.
“What we really have to start asking ourselves is what can we do as a nation to rectify the situation,” Mr Carson told ABC.
“I think we should talk about the actual facts. If we can get rid of the rhetoric from either side and actually talk about the facts, I think that’s when we begin to make progress,” he added.