Nine people were killed, nine wounded and sent to the Modern Medicine Hospital and Al Firat Hospital in Raqqa, Hawar news agency reported on Tuesday.
Children were among the wounded in dual blasts: a mine and then a car bomb.
The Syrian Observatory for Human Rights (SOHR) reported 15 people were killed in the explosions on al-Nour Street in western Raqqa.
The UK-based conflict monitor added that the area was crowded with pedestrians and there was a security checkpoint nearby.
No group immediately claimed the attack.
Last month the Syrian Democratic forces (SDF) declared the defeat of the Islamic State (ISIS) caliphate after pushing the group out of the Middle Euphrates River Valley town and villages of al-Baghouz.
Security experts have cautioned that ISIS may revert to al-Qaeda style hit-and-run, IED, and suicide attacks after the loss of the geographical caliphate.
Syria's state-run SANA news agency claimed the bombing targeted the US-led "coalition" and its "mercenaries" including the SDF.
It confirmed the location of the explosion as western Mosul near Ibn Khaldoun Al-Basel Street.
Reuters reported that SDF members gathered at the scene.
“I heard the sound of a big explosion and people were rushing and I saw people blown up with body parts,” an injured witness who was rushed to hospital told Reuters.
The outlet added that among the injured were three Asayesh (Kurdish security) members.
Raqqa city's security has been in the portfolio of the Raqqa Internal Security Forces (RISF) since it was liberated from ISIS in October 2017.
In the Raqqa countryside, there was an explosion in Tabqa that killed one man and killed his wife on Monday night.
