The defeat means the Beavers have won just twice in their last 16 games as they sit seven points above the drop-zone.
Chris Dickson's penalty wasn't enough as the Beachboys took control in the second-half at the Beveree.
"I’m disappointed and I’ve made the players aware of that," McCann told the club's video service.
"I need more from them, in times of need, we need more from them. The goals we’ve conceded today are definitely avoidable.
"I’m desperately trying to put a performance together for the home supporters. We’re putting in better performances away from home and I really wanted to put one on today, but it just wasn’t to be.
"The third goal really knocked the stuffing out of us, and we didn’t look like we had the power to recover and there were some tired performances out there."