Those must be white flies or Asphits or what ever the hell these bothersom, plant killing, bottomfeeding, assholes are called... Get you some Neem oil and some sticky traps. They will be gone in a few weeks if the aint so bad. If they are bad they are VERY hard to get rid of. Treat the plant with 1 tblsp. of Neem oil to one gallon of water, spray plant liberally making sure to get the underbelly of each and every leaf, you should use the least amount as possible, but make sure you get every inch. Do this once a week till you feel they are gone. You can also continue weekly to ensure they dont come back...
Hope this helps and i hope you kill EACH AND EVERYONE... Good Growing!!!