Central AC Tripping Circuit Breaker (sometimes)
Before you call a repair person, check the following: Look at the UL label of the outdoor unit.   Find the item marked "Minimum Circuit Ampacity."  This is the minimum size of circuit breaker required for your unit.  Verify that your tripping breaker is at least this big.  If it is too small, then you may need to upgrade the electric service to the unit.

It is normal for a compressor to pull more power during initial startup when pressure on the high and low sides have not yet stabilized and the expansion valve is fully open.  After the pressures stabilize and the expansion valve closes somewhat, there is typically a smaller load on the compressor than at startup.  The most likely cause for your compressor to over amp during startup is that the run capacitor for the compressor is a little weak.  A weak capacitor will still start the compressor, but the compressor will draw higher amperage than it is meant to.  This is a $15-$25 part.  The existing capacitor can be tested with a multimeter that checks capacitance.  If the measured value is less than 90% of the labeled value, then the capacitor must be replaced.  Make certain the replacement has an equal or greater voltage rating than the original.  The capacitance rating must be the same as the original.