Reports said a fight broke out on Sunday between three climbers – Steck, his Italian colleague Simone Moro and Jonathan Griffith from Britain – and local guides.
The sherpas are said to have attacked the Europeans physically following a verbal spat, and to have threatened them.
In a statement, Moro said the fight broke out at about 7,200 metres after the climbers had left Camp 2 for Camp 3 on Everest’s west face.
A group of sherpas rigging up ropes asked the climbers not to disturb them. The European mountaineers continued their ascent, but say they kept clear of the guides.
The sherpas then accused the climbers of climbing over their ropes and triggering a fall of ice, which had hit one of their number.
Following an angry exchange, Steck and his fellow climbers retreated to Camp 2, where they say a further 100 sherpas were waiting.
This group began kicking and hitting the climbers, and some sherpas threw stones. Steck received a cut to his lip.
After this the climbers packed up their things and headed back to base camp.
The Nepalese authorities are investigating the incident.
In a statement on his website, Steck said the three climbers had been warned they would be killed if they didn't disappear within an hour.
He said he didn’t believe that their actions were the reasons behind the attack. The European mountaineers blamed "a far more deep rooted and long term problem, which is the way that Nepalis feel treated by Westerners on the mountain".
"The three climbers would like to extend a huge thank you to all those who saved their lives at Camp 2 and to those who are now taking over the investigation," he said.