A ban on outdoor meetings of more than 10 people was extended indoors because most recent outbreaks of Covid-19 were linked to family meetings or mass drinking sessions organised by young people called botellones.
Funerals, burials, weddings and religious ceremonies as well as tourist events also faced new restrictions.
The crackdown came as Spain became the first western European country to report more than half a million coronavirus cases.
Some 8,666 people tested positive for the disease on Wednesday, the health ministry said, bringing the total to 543,379.
Spain recorded an average of 259.8 new cases per 100,000 inhabitants in the past two weeks, compared with 37.2 in the UK, and double the figure in France of 130.4.
Experts said the majority of new cases were among young people aged 24-30 but about 50 per cent of those diagnosed were asymptomatic or showed only slight symptoms.
The Left-wing government failed to warn young people of the dangers of meeting their friends before lockdown ended in June, analysts said.
Spain is reintroducing lockdown measures amid a surge of coronavirus infections (REUTERS)
Fernando Simon, Spain’s health emergency chief, appealed this month to social media influencers to help change young people’s behaviour.
But Rafael Bengoa, co-director of the Institute for Health and Strategy in Bilbao and a former director of the World Health Organisation, said: “We are playing a cat-and-mouse game but the cat is always one step behind the mouse. It is no good trying to ask social media influencers to change young people’s behaviour in September. We need to be ahead of the game, not trying to catch up.”
Professor Bengoa also blamed the rise in cases on the lack of case trackers.
He said in Catalonia and Aragon authorities failed to provide proper accommodation for migrant fruit pickers who spread the disease because they were forced to live in unhygienic conditions.
The death rate remains below the peak in April when more than 900 people died in one day. Experts say this is because younger people are catching the disease and doctors are detecting Covid-19 at an earlier stage.