Addressing an audience of police chiefs, Khamenei said officers needed plans to deal with drivers who speed, and suggested such fatalities were a product of privilege and disregard for others.
"I hear that young people from the generation of wealth, a generation intoxicated by their money, are driving luxury cars and parading in the streets, making the streets insecure," he said, quoted by his website www.Khamenei.ir.
"This is an example of psychological insecurity," Khamenei added, though he did not specifically mention either of the well-publicised crashes in Tehran in the past week.
In the first deadly incident in the early hours of Tuesday, a one-time national racing champion, Hamid Reza Kamali, and two of his friends died at high speed in a BMW, media reported.
State television showed traffic camera footage of the crash involving Kamali and three passengers -- none of whom was thought to be wearing a seat belt.
The video showed at least one person being thrown out of the convertible when it smashed into another car and then hit the central reservation.
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The car was thought to be travelling at around 200 kilometres per hour (125 mph). The smash also injured three people, including two from the other car.
A close friend of Kamali's told the daily newspaper Jamejam that he had seen the former racer before the accident and that he had not been "not under the influence".
Citing Kamali's expertise as a driver and the suddenness of the incident, he said the car must have suffered a technical fault.
A second deadly crash, also early Tuesday, saw a young girl killed when she lost control of a Porsche Boxster sports car and smashed into trees lining Shariati Avenue in northern Tehran.
The car's owner, a young man who was in the passenger seat at the time, later died in hospital from his injuries.
The car had been going so fast -- also at around 125 mph -- that it only stopped 500 metres (yards) after the first impact, according to a Fire Department official.
Despite having a good road network, Iran has a poor safety record with almost 20,000 deaths a year, predominantly caused by drivers who ignore basic rules and conduct.
Recent years have also seen the appearance in major cities, especially in Tehran, of expensive and powerful foreign-made luxury cars imported at high cost by wealthy Iranians.