"We were inside the restaurant and my friend saw at the back that many policemen had come to the Italian restaurant," he said.
"After a while we saw that all the people... in the Italian restaurant are evacuating. Then... the policemen came and all the clients in all the restaurants, they turned them out."
Eta has been held responsible for more than 820 deaths during its campaign for an independent homeland in Spain's Basque region.
In its statement earlier on Sunday, Eta claimed responsibility for July's bomb attack in Palmanova, Majorca, and for three other bombings in Spain this summer, which together claimed three lives and injured dozens more.
The organisation is marking the 50th anniversary of its founding.
Majorca is one of Spain's top tourist destinations. Eta has targeted the country's tourist industry in the past in a bid to disrupt trade and force talks.
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