Pledging with Index Option Spread

Can I use stock or cash pledge to reduce my margin requirements for a NIFTY/BANK NIFTY CALL OR PUT SPREAD ?

Example. Currently I take ATM CALL SELL + ATM+50 CALL BUY as a BEAR CALL SPREAD
This usually requires 25k - 27K of initial margins in my funds to enter the spread.
Is there some way to pledge my existing liquid bees or say stocks to further reduce my margin requirements ?

When you pledge, you increase your available(utilizable) margin which can be used to enter trades.

Why doesnt Zerodha allow me to pledge GOLDBEES ?

You can pledge GOLDBEES. Could you DM me more details along with error screenshot? Will have this checked and assist.