Here's an interesting line from the article:
The travel advisory addressed growing gun violence, mostly hate crimes, including racism and discrimination, highlighting that the traveler’s race, country of origin, ethnic background, sexual orientation or gender identity may place them at higher risk after recent attacks linked to white supremacist ideology.
Obviously, the attacks in California and Ohio are being what is referenced here, as well as perhaps the two synagogue shootings which happened earlier in the year.
Objectively, this sort of violence is absolutely nothing compared to the overall number of murders that occur in a year. In 2017, the number of homicides was 19,510 (and it was 19,362 in 2016). Oddly enough, I can't find the homicide numbers for 2018 either through the CDC or FBI, and the FBI specifically only having the preliminary report out for 2018 which just doesn't have the raw numbers. But you get the point.
I also couldn't find any travel advisory about France in 2016 or so
concenring the number of prolific terror attacks taht had been perpetrated against the French and the Jews of France in spite of the highly escalated violence. And let's remember: if we are saying that violent terrorism by white nationalists with guns
is on the rise in the USA, why was it not the case that there was concern for the terrorist incidents occurring in France in the mid 2010s? The reason is obvious: Amnesty International has a political goal here.
If they were even sincere about "gun violence" (which is not the focus here), they would point out that the overwhelming majority of gun violence has absolutely nothing to do with politics. The amount of it that is related to hate crimes is microscopic.
It's simply a biased and silly declaration if that was really the focus.
 CDC Fast Stats
 Drug War Facts (Citing the CDC