If the microwave is not a 1500 Watt microwave and is around 700 Watts then yes it's safe to use the power strip with the microwave.
If your microwave is 1500 watts then it's not recommended since the power strip isn't really designed to handle that many watts or amperage.
I have my 700 watt microwave plugged into a power strip and it works just fine for me and never had any overheating issues or problems.