By Fayen Wong
U.S. light crude for August delivery CLc1 traded at $143.78 a barrel by 0433 GMT, a touch weaker than late Friday dealing. The New York Mercantile Exchange (NYMEX) did not issue an official Friday closing price due to the July 4 holiday.
London Brent crude LCOc1 fell 20 cents to $144.40.
Oil hit a record $145.85 hit on Thursday, but fell more than $1 on Friday as traders anticipated easing tensions between Iran and the West after Tehran responded to a package of incentives to try to resolve the long-running dispute over its nuclear efforts.
But in its first public response to the offer on Saturday, Iran vowed to pursue its enrichment programme, saying it had no intention of discussing its "right to enriching uranium".
"Geopolitical concerns are still supporting oil prices. Iran sent out some mixed signals over the weekend and they haven't given any clear indication on whether they would step up with their nuclear programme or give way," said Toby Hassall, an analyst at Commodity Warrants Australia in Sydney.
"Apart from Iran, oil prices will also be dependent on the U.S. dollar movements and the U.S. equity markets this week."
Iran government spokesman Gholamhossein Elham told a news conference on Saturday: "Iran's stance has not changed (on uranium enrichment) and we are ready to hold talks in the framework of preserving Iran's nuclear rights."
On a more positive note, Iran's foreign minister on Sunday expressed optimism about what he said was a "new environment" for talks with major Western powers over its nuclear programme.
Foreign Minister Monouchehr Mottaki said recent discussions over a package of incentives from major powers aimed at getting Iran to curb its nuclear enrichment programme were "different from the previous discussions and negotiations."
Oil has gained about 50 percent this year, driven partly by the tensions over Iran's nuclear programme, plus expectations that global oil supplies will fail to keep pace with strong demand growth from newly industrialising China and India.
OPEC President Chakib Khelil ruled out on Sunday an eventual oil price fall in view of strong Chinese and Indian demand, adding geopolitics and a weak dollar were behind the current spike, Algeria's APS news agency reported.
Separately, French tuna fishermen resumed their blockade of France's Fos-Lavera oil hub on Friday to protest against the European Commission's decision to end their fishing season early.
The fishermen had removed their boats at about 0500 GMT after a first 24-hour blockade, according to port authorities, but in the late afternoon fishermen's union leaders said the boats were back blocking accesses to the port. (Reporting by Fayen Wong; Editing by Ben Tan)
