Or any long/intense cardio workouts? 
Yes. Too much cardio can lower your testosterone levels
too much weightlifting or any other training can lower your testosterone too. overtraining is not good no matter how you do it.
Why?
Yes, excessive amounts of endurance training will lower your t levels.
I used to race triathlons and adventure races.
After primal quest, a 10 day race through the deserts of Utah with very little sleep and almost constant movement, I was a broken mess.
I went to the doctor who ran a ton of blood work and what stood out was my testosterone came back at 210, I was anemic and cortisol levels were sky high.
We were perplexed as what was wrong because I was very fit and cut with extremely low body fat at the time. In other words, I didn't look like the guy with low T but I felt awful.
The doctor had no clue. I actually found a case study on line of an endurance runner presenting with symptoms of low T and put the pieces together for my self .
This was before TRT had gained popularity so I didn't do anything but continue training but at a more normal level, not the extreme distances I had been covering.
3 months later on a follow up, my T was at 750.
So, yes, endurance training can lower your testosterone but running 30 minutes a day on a treadmill is not going to do it.
Now if your training for a marathon at 80 miles a week or cycling 350 miles a week you might have some problems.