July 22 (Reuters) - Southwest Airlines LUV.N forecast third-quarter profit below Wall Street expectations on Wednesday, after renewed U.S.-Iran fighting sent fuel prices higher again, eclipsing the benefits of strong travel demand and gains from assigned seating and extra-legroom offerings.

The Dallas-based carrier expects to post an adjusted profit of 50 cents to 75 cents per share for the July-September quarter. Analysts on average estimate 82 cents per share, according to data compiled by LSEG.