AWS EC2 instance traffic spike on port 80

We received an “abuse report” from AWS indicating we may have experienced a DDOS attack. From what i could see there was definitely some spikes in the last two days. According to AWS it was through port 80 (HTTP/WEB) which we need. To be honest this is not very frequent. However i just wanted to take in some suggestions from the community on what are some should / could do’s in this situation?