March 26 (Reuters) - U.S. stock index futures were down on Thursday, following gains in the previous session, as investors remained cautious over developments in the Middle East while weighing the prospects of a de-escalation.

U.S. President ​Donald Trump said Iran was desperate to make a deal to end the fighting, contradicting the Iranian foreign minister who said Tehran was reviewing a U.S. proposal but had ​no intention of holding talks to wind down the conflict.

Conflicting signals from both sides left markets on edge, as hopes for a breakthrough to restore shipping through the crucial Strait of Hormuz remain uncertain.

"The relative calm in markets suggests some investor confidence that hostilities may eventually wind down, however slim that prospect remains," said Molly Schwartz, cross-asset macro strategist at Rabobank.

At 04:55 a.m. ET, Dow E-minis were down 242 points, or 0.52%, S&P 500 E-minis were down 39.5 points, or 0.59%, and Nasdaq 100 E-minis were down 177 points, or 0.73%.

Wall Street's main indexes closed higher on Wednesday after Washington delivered a proposal to Iran through Pakistan, while comments from Iranian officials suggested Tehran might be open to diplomatic offers even as it publicly denied any ongoing negotiations.

"Investors are trying to price out the war and price in a peace rally ahead of time, but risks remain elevated," said Ipek Ozkardeskaya, senior analyst at Swissquote Bank.

The oil price spike stemming from the conflict has revived inflation concerns, putting central banks in a tough spot with regards to interest rates.

Money market participants are no longer pricing in any easing from the U.S. Federal Reserve this year, after previously expecting about two rate cuts before the Iran conflict erupted, according to the CME Group's FedWatch Tool.

On the data front, investors will parse through a weekly reading of jobless claims numbers and comments from Fed Governors Lisa Cook, Stephen Miran, Michael Barr and Philip Jefferson.

Among individual movers, shares of Olaplex Holdings jumped 47% in premarket trading after Germany's Henkel agreed to buy the hair care brand in a $1.4-billion deal.

U.S.-listed shares of gold miners slipped as bullion prices declined more than 2%. Newmont slipped 2.8%, Sibanye Stillwater lost 3.7% and Harmony Gold shed 3%.