There really shouldn't be any play in a chainset/bottom bracket assembly, regardless of which type you're using(ie square taper, octalink, outboard etc). If there is then you're likely to possibly damage the bottom bracket frame shell threads from the movement, and you'll also be losing power when pedalling to boot.
If it's a cartridge type bottom bracket and there's actually play in the bearings becuase they're worn (as opposed to the BB not being screwed tightly into to frame shell) then it's probably time to change it.
As your description is a bit vauge it's difficult to advise further without seeing it.
Either way if you can't sort it take it to a REPUTABLE bike shop and they wil be able to advise further.