I am a muslim and I have utterd an statement unintenionally which represent shirk but i had no believe in it neither i was doing this as an act of worship.so can it be regarded as shirk or not?
In the Sharia, ‘kufr’ refers to the denial of anything Allah obliges belief in, whatever the Prophet (saw) brought from Allah proven definite and certain; having belief in that with one’s heart that it’s the truth is necessary for one to be a Muslim (believer). Therefore, a person who does not consider any of the definite teachings of the Prophet (saw) to be true or does not approve of them is called a ‘kafir’ (disbeliever).
Your uttering of a shirk word and, as you mentioned, unintentionally indicates you do not believe in what you uttered, rather you regret it. So it does not amount to shirk. Seek Allah's forgiveness and move on.
May Allah reward and protect you.
I suggest you read this, it explains the concept of Kufr in Islam.