The Millennium Time, which has a capacity of 340 and is part of a fleet operated by City Cruises, collided with a cargo vessel on the river near Waterloo Bridge and the landmark Oxo Tower this afternoon.
Police, fire and coastguard crews were called to rescue passengers who were led away from the stricken vessel after the accident.
A spokeswoman for City Cruises said: “Today at 2.25pm the Millennium Time - part of City Cruises’ sightseeing fleet - made contact with a commercial vessel while sailing by Coin Street on the River Thames.
“Seven minor injuries have been reported, none of whom were hospitalised.
“All other passengers were guided off the boat promptly by City Cruises, who continue to do everything they can to support the authorities and those involved in the incident.
“Investigations are ongoing and more information will follow pending its conclusion.
“The Millennium Time will return to Cherry Garden Pier for repair and all other City Cruises services are running as usual.”
Safety on the Thames was overhauled in the wake of the Marchioness disaster in 1989, which saw 51 people die when the pleasure cruiser hit a dredger.
Scotland Yard said today that neither boat was at risk of sinking after the collision and that it was too early to speculate on the cause of the crash.
Photographs posted on Twitter showed shattered windows at the front of the sightseeing boat, with fragments of glass scattered inside.
London Ambulance Service sent two ambulance crews, its hazardous area response team and a duty officer to the scene, and treated six patients.
Waterloo duty station officer, Christine Masson, said: “We treated six patients at the scene for a range of minor injuries. We treated a teenage boy for a graze to his leg and another boy for shock.
“We also treated two women for neck pain, one reported to be in her seventies and one reported to be in her thirties. We treated another woman, reported to be in her fifties, for knee pain.
“No patients were taken to hospital.”
The London Fire Brigade also sent its boat to the scene of the crash.
A spokeswoman said: “The fire boat has been called to reports of a collision between two boats on the Thames near Waterloo Bridge. Firefighters are assisting the police and the RNLI at the scene.”
City Cruises, that was set up in 1985 and has a fleet of 19 boats, carries more than two million passengers each year on sightseeing, entertainment and private charter trips.