Twitter's rules say that threats of violence are banned but it refused to comment on the suspension.
One of the message on the new account reads: "For what it's worth, shooting the messenger and suppressing the truth by silencing your opponents isn't quite the way to win the war of ideas."While the main Twitter account, which used to publish in several languages, had been blocked, a separate feed in Arabic continued to operate.
The new al-Shabab account has 280 followers, compared to the previous account which had more than 20,000 followers. It was closed on 25 January, about a week after it announced the killing of a French spy, Denis Allex, it was holding hostage.
Mr Allex, who was kidnapped in Somalia in July 2009, was killed in retaliation for a failed French operation to free him.
Analysts say the US has wanted al-Shabab banned from Twitter for some time, but lacked the legal means to enforce its will. Al-Shabab has been forced out of Somali's main towns over the past 18 months but it still controls many rural parts of southern and central Somalia.
For more than 20 years Somalia has seen clan-based warlords, rival politicians and Islamist militants battling for control of the country.