Not in any of the briefings I got. There is an ROE restriction that requires that we have to be fired upon first, but that's different than Law of War.
When I went through War College, I was taught the actual "Laws of War" based on existing treaties, and they are far less restrictive than commonly thought.
Running a potential firing course on anybody's naval vessel and failing to turn away on warning turns you into a target per international law.
When the Lybians MiGs got radar lock on our patrol Tomcats back in Reagan's day, the Tomcats promtly shot both Migs down, one well in international water, and one just before it crossed Lybia's claimed airspace.
The Cubans tried to cut off one of our Altus tankers during the Panama invasion, and their 2 MiGs barely won the race back to Cuba ahead of our F15s. They never got close to the tanker, who with a good head start can run a fighter out of gas.
With the attack on the Stark, the US pretty much got over the gentlemanly "wait until fired upon"in the Gulf. Although a tragedy, the shooting down of the Iranian airliner who turned off their beacon, ignored radio calls, and flew an attack profile against our Frigate was entirely legal and justified under international law. The blame lay with the Iranian pilot who performed an act of war.
As far back as the 62 Cuban crisis, one of our patrol aircraft opened the weapons bay doors over Russian ships and prompted a hotline call to Kennedy asking if we were declaring war and attacking their ships. Fortunately the only thing that sank that day was the flyer's career.