Yes, increased productivity and efficiency are deflational in nature. You can create N more things now with the same cost. The extra N things push price down if the amount of money in the system stays the same. That's why central banks inject more money into the system to "soak" up the extra economic activities, to maintain a constant and slightly upper price pressure.

When people see the price is not decreasing despite increased efficiency, they will spend the money since it worth less tomorrow.