Rules Question

[legend]

Adult league (18-25 year olds), playing under mlb rules. Im the PU. Runners on 1st. & 3rd. 1 out. Pitcher starts to do the fake to 3rd-fake to 1st. Runner on 1st breaks for 2nd on the pitchers first movement, as the pitcher is turning from the fake at 3rd he pumps his arm towards 1st and sees the base runner heading for 2nd. so he turns and throws towards 2nd to make a play on the advancing runner. Is this considered a Balk?
I called it a balk and the coach wanted to argue that because the pitcher actually threw to 2nd that it shouldn't have been called. I've read the mlb rule 8:05 and now Im unclear if i was correct in calling the balk in that situation.