Whitish bumps after any resurfacing laser treatment can be several things. The most common are milia. These are retention cysts after injury to the skin and will generally resolve on their own without any scarring other other problems.
Rarely and more seriously whitish bumps can also represent either fungal infection or bacterial infection. In these cases, medical treatment is necessary as scarring can occur. It is best to have the physician who performed your treatment examine your face as soon as possible to determine the best course of treatment, if any. If they are milia, there is no way to avoid getting them, but they tend not to be a long term problem.