In June, the quadruple world champion was locked in a tight championship battle with Vettel in Azerbaijan, when the Ferrari driver deliberately crashed into him during a safety car period.
"Seb showed more nerves this season than before," Hamilton told Stuttgarter Nachrichten.
"None of us are superman, and everyone can fail under extreme pressure. Some reached that point sooner, others later.
"It's like tennis. If [Roger] Federer plays against [Rafael] Nadal, one waits for a small weakness in the other, because half a per cent is enough."
Hamilton, meanwhile, said that he thrives under high pressure.
"You saw it at the end of the season. Suddenly I had no more pressure and was not very good," he joked.
"I compare this season with a 100 sprint by Usain Bolt.
"He often gets a bad start but then he comes back."
Hamilton expects Ferrari's Vettel to come out of the blocks strongly in 2018.
"I'm assuming that he recovers his strength for next year, but I'm not afraid," said Hamilton.
The new season gets underway with the Australian Grand Prix on March 25.