The attack came as diplomats, including U.S. Secretary of State Hillary Rodham Clinton, shuttled around the region to try to broker a cease fire following a weeklong Israeli offensive against Palestinian militants in Gaza that has killed more than 130 Palestinians. Militant rocket fire into Israel has killed five Israelis.
The bus exploded about noon on one of the coastal city's busiest arteries, near the Tel Aviv museum and across from an entrance to Israel's national defense headquarters.
The bus was charred and blackened, its side windows blown out and its glass scattered on the asphalt. The wounded were evacuated and blood was splattered on the sidewalk.
An Israeli driver who witnessed the explosion told Army Radio the bus was "completely charred inside." Another witness said there were few passengers on the bus when it exploded. The witnesses spoke to Israeli TV and were not identified.
Police spokesman Micky Rosenfeld said authorities were investigating whether the bomb had been planted and left on the bus or whether it was the work of a suicide bomber.
"We strongly believe that this was a terror attack," he said.
He said that of the 10 wounded, three were moderately to seriously hurt.
More than 1,000 Israelis were killed during the violent Palestinian uprising in the last decade in bombings and shooting attacks. More than 5,000 Palestinians were killed as well.
The last bombing in Tel Aviv was in April 2006, when a Palestinian suicide bomber killed 11 people at a sandwich stand near the city's old central bus station. A bomb left at a bus stand in Jerusalem last year killed one person.
In Gaza, the Tel Aviv bombing was praised from mosque loudspeakers, while Hamas' television interviewed people praising the attack as a return of militants' trademark tactics.
There was no official comment from Hamas or Islamic Jihad.