No they aren't. They're targeting certain vessels based on ownership and destination.
For example, Chinese ships are not targeted.
Now either name the American owned vessel(s) they targeted or admit your prevaricating.
They have sunk, so far, a (nominally) British-owned ship and a Greek registered ship. Others attacked included Singapore registered ships owned (or leased) by Maersk (Denmark), an ostensibly Indian-owned Liberian registered ship. The Houthis still seem to hold the “Galaxy Leader”, Bahamian Registered, Japan-Operated, with Israeli co-owners (plus a consortium).
Seems to me they are at war with the whole world as far as their attempts at blocking Red Sea transit.