Tommy Bowe and Rob Herring each crossed over for the visitors at the Liberty Stadium on Saturday but it was not enough to prevent Ospreys claiming a bonus-point win.
The defeat saw Neil Doak's side slip out of the GUINNESS PRO12 top four at the expense of Irish rivals Leinster.
But with clashes against both Connacht and the Leinstermen just around the corner, Best believes Ulster can quickly make amends.
"It's still very tight at the top so we are very disappointed to come away from this game with nothing and give them five points," he told the Irish Times.
"Now it's massively important that we have a big response next week against Connacht.
"We've got a big couple of weeks coming up. We want to stay in that top four but that means playing a lot better than we have over the last couple of games.
"We are hugely disappointed but we haven't lost any confidence in what we're doing. We just have to do the basics far better.
"We didn't look after the ball well and our tackling let us down. We got into good shapes but we were soft at the gain line.
"We either missed or just soaked up the Ospreys and didn't knock them down."
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