Zijn huurvoorstellen bindend?

Excuse me asking this in English. It is a quick question: I have placed an offer to rent an apartment. After a week, the owner came back saying he picked my offer from among all offers he received. However I changed my mind and I no longer wish to sign a contract (I found a better place). The owner claims that by sending an offer I am now legally obligated to sign the contract. Is this true? I feel this is very strange and he may be trying to take advantage of my unfamiliarity, but I'm not sure.