Okaz news website said the bomber died in the attack, and that no other deaths were immediately reported. The bomber was apparently headed in a car toward a mosque and hospital that are near the US consulate in Jiddah.
Most of the consulate's staff had reportedly moved offices to a new location. Sabq news website reported that two security guards were wounded in the bombing. US Embassy officials in Saudi Arabia and Interior Ministry officials could not be immediately reached for comment.
A State Department spokesperson, who was not authorised to be named and spoke on condition of anonymity, said US officials are aware of reports of an explosion in Jiddah and are working with Saudi authorities to collect more information.
A 2004 al-Qaida-linked militant attack on the US consulate in Jiddah killed five locally hired consular employees and four gunmen. The three-hour battle on the heavily guarded compound came amid a wave of al-Qaida attacks targeting Westerners and Saudi security posts.
More recently, Saudi Arabia has been a target of Islamic State group attacks that have killed dozens of people. The extremist group views the Western-allied Saudi monarchy and government as heretics.
Saudi Arabia is part of the US-led coalition fighting the IS group in Iraq and Syria. In June, the Interior Ministry reported 26 terror attacks had taken place in the kingdom in the last two years.
Local affiliates of the IS group have targeted minority Shiites and security officials.