How can take legal action against who borrowed money and cheated me?

He's not commited a criminal offence, I'm sure its a civil matter you may be able to claim in a small claims court but I'm unsure of the legalities with these matters in Bahrain, Try visiting him tell him if he pays small amount each week you'll be happy with that.

Look, contrary to whatever you may heard, a travel ban cannot be just slapped on anyone at your discretion.  It has to be ordered by an execution court and only after the case has been heard with the required proofs in a civil court.   

And whatsapp messages are not exactly proofs that can stand up in court that easily.  Even banks which make you sign dozens of contracts with legal language have a tough time recovering the money due to them. 

Most people just go to the police and ask them to call the guy that owes the money.  Usually people get scared into giving it back but the police doesn't arrest them or make any case.

My suggestion would be to consult a lawyer, show him all the details and have him guide you.

or her