A spokeswoman said the decision was made after last month's Malaysian Grand Prix, where the track is similar in characteristics to Bahrain, to bring the hard and medium compounds rather than hard and soft.
The medium and soft options were used in China last weekend, with some drivers doing the minimum number of laps in the faster but far less durable softs.
Seven laps in the race, won by Ferrari's Fernando Alonso, was the longest anyone did on the soft tyres.
The original allocation for Bahrain was decided in December, long before the start of winter testing. Soft and medium were used last year, with drivers having to use both.
Bahrain is a fast-flowing layout made more abrasive by the sand blowing in from the nearby desert. Tyre degradation is expected to be reasonably high.
"It's one of the most demanding tracks of the year for the tyres, mostly because of the high ambient and track temperatures. We expect about three stops per car," said Pirelli's motorsport director Paul Hembery in a race preview.