U.S. stock index futures were mixed on Tuesday as investors awaited key inflation data and the start of earnings season for major Wall Street banks, while escalating tensions between the United States and Iran pushed oil prices higher, raising fears of renewed inflationary pressures.

Dow Jones futures fell 0.2%, S&P 500 futures declined about 0.01%, while Nasdaq 100 futures rose 0.5%.

JPMorgan Chase, Goldman Sachs, Wells Fargo, and Citigroup are scheduled to kick off second-quarter earnings season on Tuesday, with investors eyeing the financial results for early indicators on U.S. corporate performance and economic demand.

The earnings season represents a key test for this year's stock rally, after strong performance in several sectors drove the S&P 500 to gains of nearly 10%.

Inflation and energy prices under scrutiny

Investors are awaiting the release of June Consumer Price Index data, scheduled for 8:30 a.m. ET, with expectations of a slowdown in inflation last month.

However, this expected slowdown may not be enough to reassure markets amid rising tensions in the Middle East and their potential impact on energy prices, which could reignite inflationary pressures and keep the Federal Reserve cautious on its monetary policy path.

Ipek Ozkardeskaya, senior analyst at Swissquote Bank, said: 'Gasoline prices have already exceeded June levels, meaning the next inflation report could reflect a sharp rise in prices. Therefore, the CPI data may be less significant than developments in geopolitical tensions.'

The data release will be followed by remarks from Federal Reserve Chairman Kevin Warsh, who will present the central bank's semi-annual monetary policy report to Congress at 10 a.m. ET.

Interest rate expectations weigh on investor sentiment

Comments from Federal Reserve Governor Christopher Waller, which had a more hawkish tone, heightened investor concerns after he indicated on Monday that the central bank may have to raise interest rates 'in the near term' if inflation remains significantly above its 2% target.

According to the CME Group's FedWatch tool, traders' expectations for a 25-basis-point rate hike at the Federal Reserve's July 29 meeting rose to 43%, up from 34% the previous day.

These expectations, along with the third consecutive night of U.S. military strikes on Iran and the possibility of imposing a 20% fee on ships crossing the Strait of Hormuz, kept markets cautious, while oil futures rose to their highest in four weeks.

Tech stocks improve after sharp losses

As of 5:13 a.m. ET, Dow Jones futures were down 118 points, or 0.22%. S&P 500 futures also fell by about one point, or 0.01%.

In contrast, Nasdaq 100 futures rose 142.75 points, or 0.48%.

The rise in Nasdaq futures followed a 1.6% decline in the index, which includes major technology companies, during Monday's session.

Shares of chipmakers stabilized in premarket trading after the sharp losses recorded in the previous session, while the iShares Semiconductor Index rose 2.4%.