By Timour Azhari and Parisa HafeziDUBAI, July 28 (Reuters) - Oman has presented Iran with a plan backed by Gulf states to manage the Strait of Hormuz, including collecting voluntary fees for using it, a Gulf source and a Western diplomat told Reuters on Tuesday. Iran has ​denied seeking to resume talks with the United States. Iran effectively shut the strait to ships other than its ⁠own after the United States and Israel attacked on February 28. A deal last month between the United States and Iran partially reopened it, with future talks planned to resolve larger issues including Iran's nuclear program. But the agreement collapsed in early July after Iran fired on ships using a channel it does not approve.