Unmanned Aerial Vehicles (UAVs) present unique security challenges due to their distributed nature and susceptibility to evolving threats. Current Intrusion Detection Systems (IDS) struggle to keep pace with real-time and zero-day attacks, necessitating innovative approaches tailored specifically for UAV environments. This study proposes a Unified Intrusion Detection System (UIDS) designed to bolster UAV security by leveraging a Lightweight Multi-Tier IDS architecture. Our framework integrates multiple detection units deployed across UAV networks, enhancing detection accuracy while minimizing resource consumption. By optimizing the Aho-Corasick algorithm and incorporating Honeypot Intelligence, our system not only identifies known and emerging threats but also facilitates the creation of IDS signatures through collaborative knowledge sharing and honeypot integration. Experimental results demonstrate superior detection rates and reduced false positives, validating the efficacy of our approach in safeguarding UAVs against malicious intrusions. Notably, the Lightweight Multi-Tier IDS achieves significant improvements in detection rates, response times, and proactive threat detection capabilities, boasting an impressive overall detection rate of 99.71% against UAV intrusions.