(Updates with index/price moves and geopolitical news from the first paragraph.)
US equity indexes traded mixed, with communication services and technology sectors helping lift the Nasdaq Composite and the S&P 500.
The Nasdaq rose 0.9% to 25,752.1, with the S&P 500 up 0.5% to 7,493.2 in midday trading Monday. The price-weighted Dow Jones Industrial Average, which is home to old economy sectors, fell 0.2% to 52,065.3.
Consumer staples, materials, and healthcare led decliners. Energy was among the top three gainers as investors weighed geopolitical developments.
US Secretary of State Marco Rubio said Sunday night the US "remains open" to talks despite the weekend's violence, and an Iranian official said their side was similarly open to discussions, CNN reported.
Iranian Interior Minister Eskandar Momeni is heading a high-level delegation to neighboring Pakistan at the invitation of his Pakistani counterpart, news reports said Monday. The trip comes after Iran's Foreign Ministry announced mediators continue to exchange proposals to get peace talks back on track after nearly two weeks of bombardment.
The front-month US West Texas Intermediate fell 0.6% to $81.32 a barrel, and global benchmark North Sea Brent slipped 0.2% to $87.93 a barrel.
Meanwhile, Yemen's Iran-aligned Houthis said on Monday they were imposing a naval blockade on Saudi Arabia, a move that widens the threat to global energy supplies and trade beyond the Gulf, Reuters reported.
Most US Treasury yields rose, with the 10-year jumping 4.9 basis points to 4.59%. The two-year surged 4.7 basis points to 4.22%.