NEW YORK, July 10 (Reuters) - U.S. drivers have seen gasoline prices climb again after weeks of steady declines, as renewed fighting between the U.S. and Iran lifted crudeoilprices to their biggest weekly rise in eight weeks. Disruptions in the global refining system and robust U.S. fuel exports further tightened supplies, and average pump prices rose 6 cents this week to $3.88 a gallon on Friday, AAA data showed. It was the biggest weekly increase since mid-May.