Tanzania's President elect John Pombe Magufuli salutes members of the ruling Chama Cha Mapinduzi Party (CCM) at the party's sub-head office on Lumumba road in Dar es Salaam, October 30, 2015. REUTERS/Sadi Said

DAR ES SALAAM (Reuters) - Tanzania’s President John Magufuli said on Friday he would crack down on troublemakers “without mercy”, a day after the opposition called for anti-government demonstrations on Sept. 1.

Magufuli has won some praise from Western donors for sweeping anti-corruption drives since coming to power in November.

But opponents have accused him of becoming increasingly authoritarian, undermining democracy by curbing political activity and restricting live TV coverage of parliamentary sessions.

“Do not test me,” Magufuli told a crowd in central Tanzania, according to a statement from the presidency.

“I don’t want violence in this country ... I will deal with anyone who causes violence thoroughly and without mercy,” he said.

Magufuli, nicknamed “The Bulldozer” for the way he pushes through projects , said he will not allow anyone to stand in his way and delay his plans.

The main opposition CHADEMA party said on Thursday it would hold nationwide rallies and anti-government protests “come what may”.

“We will hold these rallies and demonstrations in defiance to the order issued by the president and the police (banning such rallies),” CHADEMA chairman Freeman Mbowe told journalists.