I had the same with one of mine, my little boy put him on the floor & he kept striking. its fear, open space & you are a huge predator..just the fight or flight instinct..I got my boy to pick him up from behind, if you pull away they see it as working, try to ignore it..my little boy had him out the following morning, not happened again :)
We got a really defensive/aggresive pastel, perseverance..shes fine now..just ignore the striking & hissing its usually just bluster