This is a margin call. You essentially, borrowed monies from your broker. Understand that the broker will protect its interests because huge losses you incur when you use margin, they will have to eat up before, they go after you. Closing the trade is the right thing to do for the broker. If not, you would have had larger losses. Naked calls is highly risky and you got into a trade without even understanding the risks. It is on you buddy. Read up on options and the various risk profiles before placing another trade.