(CNN) Conservative commentator Ann Coulter vowed to proceed with a scheduled speaking event at the University of California, Berkeley, despite the school's decision to call it off.

Citing security concerns, the school's vice chancellors said they intended to "reschedule her appearance for a later date."

In a letter to Berkeley College Republicans, who organized the event, Vice Chancellors Scott Biddy and Stephen Sutton said campus police were unable to find a "suitable venue" for the April 27 event.

"Unfortunately, UCPD determined that, given currently active security threats, it is not possible to assure that the event could be held successfully -- or that the safety of Ms. Coulter, the event sponsors, audience, and bystanders could be adequately protected -- at any of the campus venues available on April 27th," the letter said.

"We realize that this is disappointing news, but the good news is that UCPD and Student Affairs remain firmly committed to working with you to find an alternative time and date for Ms. Coulter to come speak here at Berkeley. We expect most Mondays and Tuesdays in September during the day should work, though we will of course need to work through the details."