King Salman slammed Iran's "blatant interference" in regional affairs.
Saudi Arabia, which takes over the rotating chair of the Arab summit from Jordan, announced that the current gathering would be named the "Quds (Jerusalem) Summit", a reference to U.S. President Donald Trump's decision previous year to recognize Jerusalem as the capital of Israel which Arab states condemned.
The final statement released by the league declared the move "null and illegitimate".
Saudi tensions with neighboring Qatar were also on display at the summit.
Saudi Arabia and its allies have expressed support for Saturday's missile strikes by the United States, Britain and France against alleged chemical weapons facilities in Syria, while Iraq and Lebanon condemned the strikes.
Saudi Arabia's king turned his attention with long-time foe Iran - only 160 kilometres (100 miles) across the Gulf from Dhahran.
The Arab League called on Sunday for an worldwide probe into the "criminal" use of chemical weapons in Syria and condemned what it saw as Iran's interference in the affairs of other countries.
The Custodian of the Two Holy Mosques reiterates condemnation and rejection of the United States Administration's decision on Jerusalem, lauding the global consensus rejecting the U.S. decision.
"We reiterate our rejection of the USA decision on Jerusalem", the king said in a speech in Dhahran in eastern Saudi Arabia.
"East Jerusalem is an integral part of the Palestinian territories", he stressed.
"There is no contradiction with having very strong strategic ties with the United States while telling your friends where their policy should change", Jubeir said in response to a question by AFP.
At a preliminary meeting in Riyadh on Thursday, Arab ministers focused heavily on blocking the embassy move, unanimously condemning Trump's decision and moving to block Israel's bid to secure at seat at the UN Security Council this June.
His comments came just days after his son, powerful Crown Prince Mohammed bin Salman, 32, told reporters during a US tour that Israel also had a "right" to its own state.
Sheikh Mohammed bin Rashid, the Vice President and Ruler of Dubai, arrived in Saudi Arabia yesterday, ahead of leading the country's delegation to the 29th Arab League Summit.
Saudi Arabia and Qatar, which both voiced support for the strikes, remain locked in a months-long diplomatic standoff, with Riyadh accusing Doha of supporting extremists and being too close to Iran.
Despite widespread Arab condemnation of the suspected chemical attack, the Dhahran summit is unlikely to call for Assad to step down.
Among the leaders in attendance was Sudan's Omar al-Bashir, who walked the red carpet and was greeted by King Salman.
Saudi officials have welcomed Malaysia's participation in Gulf Shield 1, the biggest joint military exercise in the Arab region.