The procedural drama, which starred David Caruso, was axed by the network in May - the first show in the CSI franchise to be dropped.
© CBS
© CBS
"It was a very big deal," Tassler told reporters at the Television Critics Association press tour. "That show has been extraordinarily successful for us.
"What we looked at was [the flow on] Friday versus Sunday night. It was a very tough choice, but... it had to do with the schedule."
Tassler also defended the decision to renew the Gary Sinise-starring CSI: NY, TV Guide reports, promising that the show's ninth season will contain more humour and "big, New York-centric event stories".
CSI: Miami star Eva LaRue (Detective Natalia Boa Vista) recently told Digital Spy that she was disappointed with how the series ended.
"I was sad because we did not get a chance to say goodbye to the fans or to each other," the actress said of the show's lack of a proper finale.
> CSI: Miami axe defended by CBS boss: 'It was the odd man out'
The final series of CSI: Miami is currently airing in the UK on Channel 5 on Saturdays at 10pm.
Watch a promo for the final season of CSI: Miami below:
