George Michael will undergo sur gery this week to clear up a prob lem with the voice that has taken him to the top of the pop charts with his "Faith" album. Because of recurring throat problems, Michael had exploratory surgery last week and doctors discovered a cyst on his vocal chord. The removal operation and ensuing rest period will force him to cancel shows set for June 30 and July 2.

Michael intends to open the North American leg of his tour as sched uled on Aug. 6 in Washington, D.C.