A "strict embargo" means a complete ban or restriction on something, where no exceptions or allowances are allowed. It is like a rule that must be followed very strictly and cannot be ignored. Full definition
Rules Don't Apply is still under strict embargo until its AFI Fest premiere date but this new trailer gives a pretty good idea of the film overall, with the wonderful Warren Beatty front and center as Howard Hughes. (awardsdaily.com)
They've done so without seeing the movie; it's being kept under strict embargo. (oregonlive.com)
Prominent amongst these were early video games, and since computer technology was subject to strict embargoes, citizens of the German Democratic Republic did their best to have equivalent fun with Soviet replicas of popular Western games. (canadianbusiness.com)