This depends upon what you mean by interefering and in what context you are talking about the "interference."
For example, if we are talking about some sort of atrocity or illegal conduct (not likely with Canada) that goes against a treaty Canada has signed, then yes, the UN should have the power to do this. For example, if Canada were to seek a nuclear weapons program, the UN should have the power to impose sanctions on Canada for doing this. Another example of something like this (Rwandan genocide) is in the eNotes link below.
\In general, though, the UN should only have the power to interfere in the government of a country if A) the country has signed a treaty allowing the interference and/or B) if the country is doing something completely abhorrent to all civilized sensibilities.
The word "interfere" has some rather strong negative connotations. Interference in work of government of any country by any external agency cannot be justified. However, countries do need to influence each other to achieve common good. Similarly, an international organizational like United Nations also needs to be in a position to influence the actions of various countries, including that of Canada.
It will not be wise to oppose any pressure put by the United Nation on ant country just on the ground of it being an interference in internal matter of that country. Each such instance of interference must be examined in terms of the its objective and the effect. If the action is in joint interest of the member countries of the United Nations, without being unjust to the people of Canada, then such action is quite likely to be justified in terms of duties and responsibilities of the United Nation.